Linguistic development of Genie

Genie (born 1957) is the pseudonym of a feral child who was the victim in one of the most severe cases of abuse, neglect and social isolation on record in the medical literature.

In the first several years after Genie's life and circumstances came to light, psychologists, linguists and other scientists focused a great deal of attention on Genie's case, seeing in her near-total isolation an opportunity to study many aspects of human development. Upon finding that she had not learned a language, linguists saw Genie as an important way to gain further insight into acquisition of language skills and linguistic development. Scrutiny of their new-found human subject enabled them to publish academic works testing theories and hypotheses identifying critical periods during which humans learn to understand and use language.

Upon being removed from her parents' house, Genie gradually started to acquire and develop new language skills. On broader levels her language development followed some normal patterns of young children acquiring a first language, but researchers noted many marked differences with her language acquisition. The size of Genie's vocabulary and the speed with which she expanded it consistently outstripped both researchers' anticipations, and many of the earliest words she learned and used were focused on observable properties of people or objects, very different from those of a typical first-language learner. However, she had far more difficulty with acquisition of basic grammar and syntax, resulting in her vocabulary being much more advanced and sophisticated than most people in equivalent phases of learning and using these rules, and her acquisition of them remained far slower than normal. In addition, tests on her brain found discrepancies far larger than any prior observations of people with fully intact brains, which affirmed existing postulations on brain lateralization and gave rise to many new hypotheses on lateralization and its effect on language.

Genie's case has been compared extensively with that of Victor of Aveyron, an eighteenth-century French child who similarly became a classic case of late language acquisition and delayed development.

Genie spent most of her first thirteen and a half years of life locked inside a bedroom, strapped to a child's toilet or bound inside a crib with her arms and legs immobilized. During this time she was almost never spoken to, and as a result did not acquire a first language. Her abuse came to the attention of Los Angeles child welfare authorities on November 4, 1970.

Initial assessment

When Genie was first discovered by California authorities she was admitted to Children's Hospital Los Angeles, and physician James Kent attempted to discern her ability to communicate. Kent noted that while Genie demonstrated some non-verbal ability, she could only communicate a few very basic needs. Doctors immediately noticed that she showed no understanding of any grammar whatsoever, and only responded to about 15–20 words; she knew "mother" and "father", a few color words, and a few other miscellaneous words for objects such as "jewelry box", "door", and "bunny". Her active vocabulary consisted of just two short phrases, "stop it" and "no more". Kent described the very few vocal sounds she made as, "a kind of throaty whimper." At first, hospital staff could not tell whether she had no language or if she was only selectively mute. Tests found that Genie always responded to the very few words she knew as if they were spoken in isolation, and she could not respond to very basic commands. Doctors found no evidence of any metabolic disorders or skull deformations, a neurologist could not find signs of neurological disorders, her chromosomes were normal, and an EEG had no indications of any mental disorder. After testing Genie and checking existing medical records, which also uncovered no clear mental disabilities, researchers determined she had not acquired a language. Kent said that, despite her lack of language, he was immediately certain that she had memories of her past, but she had no way of communicating them to anyone.

Early communication progress

After four months of therapy Genie's active vocabulary was over 100 words, and she showed comprehension of many words which she did not say herself. After another month she began spontaneously producing one-word answers, although her speech was difficult to understand. Her vocabulary steadily increased, and soon after her producing her first one-word utterances she appeared to understand some give-and-take of conversation and could spontaneously provide one-word responses. Her acquisition to this point was far more rapid than what the hospital's doctors had anticipated, giving them a sense of optimism and heightening their expectations of her potential for learning language. Most of her vocabulary at this time consisted of colors, the numbers 1 through 5, the word "mama", the verbs "stop it" and "spit", and a few other miscellaneous nouns such as "people" and "doctor". Even at this phase, she could distinguish between similar objects even if they were unfamiliar; she quickly drew the distinction between a pen and a marker, and did not mistake one for the other. Researchers noted her focus on objective properties was unusual, as these require a fairly high level of sophistication. The vocabulary of most young children at this phase of language learning primarily consists of nouns and a few particles, but Genie's early lexicon had almost the same number of adjectives and verbs as nouns. Before she began forming two-word sentences she could both ask for something and associate an object with someone, which was normal, but unlike most young children could also ask about memories or future events which had previously been mentioned. Hospital staff also observed she would frequently say "No" without meaning it.

One day in May 1971 when Genie was with Jean Butler, Butler asked a boy holding two balloons how many balloons he had; when the boy said "three", Butler said Genie appeared startled and quickly gave him another balloon. This was seen as a significant step, as it demonstrated that she was listening to other people, she understood significantly more language than she produced, and that she could count to at least some degree. By the time Curtiss met Genie, she was extremely eager to expand her vocabulary; Curtiss said Genie frequently grabbed her hand and pointed it towards objects for which she wanted to know the word. If Curtiss could not figure out exactly what Genie was looking for, Genie refused to let go until she learned at least one new word. Genie seemed particularly eager to learn the words for colors, expressing disappointment if Curtiss could not name a color she wanted to know. In June 1971 Genie began to use her first words with two morphemes and began to construct her earliest two-word sentences, all of which were modifier-noun or noun-noun constructions such as, "More soup" or, "Genie purse". Whereas most children start forming two-word sentences with a few core words, which they then attach to other words (often referred to as a "pivot-open"), Curtiss never observed Genie doing this.

Genie gradually began to express more of her emotions outwards, and her nonverbal communication skills quickly became exceptional; everyone who met her said she had an indescribable way of capturing and eliciting emotions, and she seemed able to communicate her desires to people without talking. When Curtiss and Kent went to toy stores with Genie, they frequently found that complete strangers had bought something for her because they sensed she wanted it, and both of them were amazed that these gifts were always the types of objects she most enjoyed. One day as Curtiss and Genie waited to cross a street, Curtiss was stunned when a woman stopped at an intersection, emptied her plastic purse, and jumped out to give it to Genie; the entire time, Genie never said anything. Genie had also befriended a local butcher without ever having to speak to him, and Curtiss said he would always give Genie a small piece of meat which she would study, smell, and rub on her lips before eating. David Elkind took her on a walk through Griffith Park and said she was fascinated by everything around her, and like Curtiss and Kent noted how intently she explored her surroundings. On these trips outside the hospital, Curtiss would deliberately act silly to help Genie release some of her pent-up tension. Her doctors, at that time, predicted completely successful rehabilitation.

Language progress

Before testing

Children typically begin to use two-word phrases when they have a vocabulary of about 50 words, however, Marilyn Rigler and Curtiss both noted that Genie only began to do so after she could use and understand about 200. Researchers noted this matched the timeline observed in children with various types of aphasia. Even then, when she first moved in with the Riglers she remained mostly quiet. After she settled down in her new surroundings her speech, which although much like her general behavior still frequently exhibited considerable latency, began to improve. She soon began to understand negative forms, albeit much more accurately and consistently with expressions using the word not (regardless of whether it was used in its full form or as part of a contraction) than with the prefix un. In September 1971, she began incorporating verbs into her two-word utterances, such as, "Dave hurt", although at first she never included the first person subject and inconsistently included any subject. When Genie first moved in with the Riglers, she did not usually listen to anyone unless she was being directly addressed or Curtiss was playing classical music on the piano. Only two months later, in mid-October 1971, Curtiss was reading Genie a story when she saw Genie was clearly listening to her; after that point, she began paying attention to people even when they were not speaking directly to or about her. Sometimes, she would even spontaneously contribute to an ongoing conversation.

The scientists observed that, unlike most young children acquiring a first language, Genie's speech always showed appropriate specificity. Whereas children's early speech is normally excessively specific, Genie never exhibited this in her spontaneous utterances. Similarly, she never overgeneralized words for individual objects, such as using the word ball to describe any round object. Even during her one-word phase of language acquisition, when Genie encountered something for which she did not know the word, instead of attempting to use her existing vocabulary she sought the correct word or phrase. For instance, when she first recognized the difference between a pen and a pencil she sought the different words for each instead of referring to both by the same term. At the same time, Curtiss noted that when Genie learned the word dog she used it to describe any dog, but never used it when describing any other animal, indicating she understood how to use generic terms. In a review of Curtiss' dissertation, language psychologist Susan Goldin-Meadow suggested this lack of overgeneralization may have been due to differences between the mind of a young child versus an adolescent as opposed to the properties of early language acquisition.

Furthermore, although Genie's two-word sentences showed many of the same syntactical properties as those of young children, she was much better at labeling and describing emotions and concrete objects, especially colors, sizes, and qualities. Two of her early adjectives were "funny" and "silly", not words usually in the lexicon of children at this phase, and most of her earliest two-word sentences modified nouns, such as "yellow balloon" and "lot bread". Taken with her ability to distinguish between general and subordinate terms, this strongly indicated a focus on physical characteristics to a degree not normally found in children acquiring a first language, who are typically better at describing relationships. She had no difficulty with classification, and never confused gender in her speech. Genie also had significantly more action verbs than normal in her early vocabulary. Tests initially administered in October 1971 showed that while she did not use the plural forms of words and could not distinguish between plural and singular words or inflections, she clearly knew the difference between one versus more than one object and understood numbers and quantitative descriptors such as "many" or "lots of". At the 1972 American Psychological Association conference Fromkin said that by November 1971 Genie's speech was "strictly rule-governed", and indicated that Genie's grammar was similar to a typical 18 to 20 month old.

During testing

Thorough testing of Genie's linguistic abilities began in October 1971, when Curtiss and Fromkin decided her linguistic abilities would yield results. These tests continued throughout her stay with the Riglers. Largely based on the data from these tests, from 1973 to 1975 Curtiss and Fromkin published four of the earliest papers on Genie; combined, these covered her progress from 1971 to early 1975. Curtiss conducted most of the tests herself, once a week almost every week, and she, Fromkin, and the research team analyzed the data from these sessions. Curtiss also recorded many of her sessions with Genie on film, and continued to observe Genie's progress outside the test settings. Between these and other evaluations of her social and psychological progress, the scientists speculated she may have been more tested than any other child. The scientists considered her progress with language to be a substantial part of their larger goal of helping her to ingratiate herself into society, so although they wanted to observe what vocabulary and grammar Genie could acquire on her own, out of a sense of obligation they assisted her whenever possible.

Ursula Bellugi and Edward Klima had noted in March 1971 that Genie seemed to know far more words than she would spontaneously say, but they could not tell what cues she used to respond to other peoples' speech. They had recommended using tests and games to establish her comprehension, as these would more accurately pinpoint her linguistic abilities, and emphasized that non-language cues such as tone of voice and facial expressions had to be eliminated to get the best results. Designed with their advice in mind, Curtiss and Fromkin's tests were intended to measure both Genie's vocabulary and her acquisition of grammar and morphology. The earliest tests they administered were deliberately short, only looking for six to eight responses per test. Because they recognized physical and emotional factors still inhibited Genie's speech at the outset, researchers included writing and visual aspects in the tests to get a fuller picture of Genie's linguistic abilities. Some of their tests involved Genie pointing to or arranging words and letters written on cards, a method Jean Marc Gaspard Itard pioneered with Victor of Aveyron, which helped Genie learn to read and write simple words. They also made sure to use words with which Genie would be familiar. Most of their tests only required Genie to point, which the scientists thought would be easiest for Genie since she already understood and used pointing. Sometimes Curtiss and Genie would invent and act out sentences together as well, which Genie found especially fun; she already used her own invented gestures to supplement many words, and when doing exercises acting out sentences Curtiss said she began wildly gesturing.

When Curtiss first started testing Genie she found that although Genie did not resist, she never initiated tests and her participation was very minimal. She seemed only to do the absolute least amount required, which Curtiss later attributed to Genie simply being lazy, which made it difficult to draw definitive conclusions from the earliest tests of Genie's progress. As Curtiss continued her testing Genie grew to largely enjoy being tested and became much more cooperative, though she sometimes playfully gave deliberately wrong answers, and would sometimes indicate that she wanted to take the tests. As testing continued the tests were gradually modified, eventually becoming longer and more complicated. Both she and David Rigler said Genie wanted to do well during test sessions to make the scientists happy, and exuded self-confidence and pleasure when finished.

In their publications, the scientists anticipated the question of whether emotional factors affected Genie's ability to learn and produce language. Curtiss acknowledged that at the outset, Genie's emotional profile may have been at least part of the reason she had been mostly taciturn. In 1975 she said that emotional difficulties contributed to her unwillingness to speak to at least some degree, which complicated their efforts to discern her true level of comprehension. However, she and Fromkin argued that while Genie's childhood had obviously left a very substantial impact on her, it had not been traumatic and therefore could not have significantly impeded her ability to acquire language. Some later writers, such as Geoffrey Sampson, found this to be extremely implausible; however, many linguists who later wrote about the case, including Noam Chomsky and Derek Bickerton, accepted Curtiss and Fromkin's assessment.

1971–1973: Early testing

Curtiss initially found that although Genie's comprehension was clearly ahead of her production, it was only slightly ahead. As testing continued the gap between them grew larger, but by 1975 the scientists wrote that her progress with speech production was well behind her comprehension but both were improving at a parallel rate. By late 1971, Genie's two-word sentences were almost always in either subject-verb or verb-object order, which they suggested meant Genie was grasping the subject–verb–object sentence structure typically used in English. She could follow other word order rules as well, as evidenced in her verb-complement sentences. At the very beginning, word order was the only non-vocabulary skill she could use in her sentences. Soon after testing Genie had also begun to use some regular past tense forms of verbs, correctly using the suffix -ed, though it would be considerably longer before she began utilizing the past tense of either irregular past tense verbs or strong verbs—which use ablaut to indicate past tense—such as to give or to break. Researchers only observed her using the latter, either in imitation or spontaneous speech, in 1973, and her spontaneous production of them remained limited. Shortly after testing began, in November 1971, she began forming noun-predicate two-word utterances such as, "stocking white". It was around this time that she produced her very first three- to four-word utterances, although they were extremely uncommon at this point. These were all either modifier–noun sentences, such as, "little white clear box" or subject–verb–object sentences such as, "Tori chew glove". This was seen as a major sign of progress, but the scientists also noted that, whereas most children progress beyond the two-word sentence stage after around four to six weeks, Genie had not done so for five months. In these sentences, she began explicitly using pieces of grammar and syntax which the scientists had thought she knew but had been unable to confirm. They specifically noted that she started including the first person subject; whereas prior to this time she would have said, "Love Curtiss", she started saying, "Genie love Curtiss". For the scientists, this was confirmation that Genie understood subject–verb–object word order. In addition, in these longer sentences she could incorporate what would have previously been a modifier-noun or possessive utterance into a longer sentence; for instance, the sentence, "More soup" became, "Want more soup".

Before December 1971, Genie could only use one noun at a time in a sentence. For instance, if she saw a cat and a dog hurt she would say, "Cat hurt" and then, "Dog hurt" as two sentences. But beginning in 1972, Genie could form and use increasingly complex noun phrases in ways that were clearly not imitative; in early 1972, when asked to describe a photograph, she said, "Curtiss, Genie, swimming pool". Although Genie rapidly showed full comprehension of regular plurals and never incorrectly used the s ending, she only started using them in her speech in her speech in January 1972 after Curtiss devised a test specifically designed towards getting Genie to utilize plurals. After this and practice with pronouncing the final -s Genie sometimes used regular plurals while talking, but even after full comprehension would only occasionally do so; in addition, she was never recorded using any irregular plurals.

Throughout January and February 1972, Genie began gaining use of comparatives and some prepositions; scientists noted she could use next to, beside, behind, in, at, front, and after. By 1973 Curtiss noted the first instances of Genie including them in her adverbial phrases, such as, "In hospital, shot hurt arm", although she noted that they were still frequently deleted in her speech. In early 1972, scientists observed the first construction of verb phrases in Genie's speech, as well as the first time she used multiple verbs in one sentence. After three months, she began combining these verb phrases with similarly expanded noun phrases. Her first locative sentences were also from this time, although they were always in either noun-noun or verb-noun form and contained no prepositions. By late 1973 and early 1974, her locative sentences had expanded to, "Like good Harry at hospital". In July 1972, the scientists noted Genie's first verb-verb phrase sentences, such as, "Like chew meat". She then quickly began using complex verbs with complex noun phrases, as in the sentence, "Want buy toy refrigerator". After another month, in August 1972, Genie could correctly use the word on—although at that point it was not completely clear if she distinguished between on and in—and could use the suffix -ing to describe events in the present progressive. These were the first grammatical markers observed in her speech, and both are normally two of the first grammatical markers young children are able to use. She was also never observed using the -ing for anything other than the present progressive. However, she did not use this with the verb to be until the fall of 1973, and then only when speaking in the first and third-person. Even after learning the present progressive, she also did not give consistently correct responses to these sentences on tests. In December 1972, after Curtiss and Genie had accidentally been locked out of the Riglers' home, Curtiss said to Genie, "Tell them [David and Marilyn Rigler] what happened" and Genie pointed to the door and said, "Tell door lock". This indicated she had some degree of recursion in her grammar, which was considered a major gain.

Genie had also begun using the genitive case in her early two-word sentences; in November 1971 many of her sentences were to indicate possession, such as, "Marilyn bike", but she still relied entirely on word order. Tests in January and February 1972 which included sentences such as, "Point to the cat's foot" and, "Point to the foot of the cat" yielded only 50% correct answers, but after March of that year she demonstrated full comprehension of both constructions despite not using them in her speech. After two more months, in May 1972, she began to use the verb have in possessive sentences, i.e., "Miss Fromkin have blue car." By 1974 she began adding the possessive my to these sentences, and was able to correctly use the marker 's to indicate possession; she was never observed attaching the 's to the wrong word.

In February 1972, the scientists observed Genie beginning to use negative sentences, all consisting of "No more"—which she had known upon admission to Children's Hospital—followed by either a noun or a noun and a verb, e.g. "No more take wax". Four months later, she began to use "No more" with only a verb, such as, "No more have". By October 1973, she could use no, not, and no more, and showed clear understanding of more complex forms of negation. But while children usually quickly progress to saying "Not have toy" and then "Do not have toy" (and quickly learn to use contractions for the negative forms of words, such as don't) Genie did not reach the "Not have toy" stage for three years. Although she quickly began to appropriately use no and not in her speech, until 1975 she could only use them at the beginning of a sentence, such as, "Not good fish tank". Until then, she would simply append the negation to the beginning what could have been a standalone utterance.

Genie slowly began using some determiners in her sentences, starting by imitating the definite article the. In the spring of 1973 she began to use the determiner another, as in the sentence, "Another house have dog", and by late 1973 she began consistently including a in noun phrases. Although she could use both definite and indefinite articles, even by 1977 she did not distinguish between the two. She also did not use demonstratives, such as this or those, or numbers in these early spontaneous noun phrases, and in 1977 Curtiss noted that Genie had still never used any demonstratives. In the spring of 1973 Genie began regularly using verb particles in her spontaneous utterances, and around the same time she began to form imperative sentences using the vocative, as in, "Go way Joel, finish story!", which suggested not only progress in her language comprehension but an increasing level of self-confidence and self-concept. However, this was tempered by the fact that despite her ability to use and comprehend imperatives, she very rarely would. Although she responded if called she would almost never call someone to her and, despite repeated encouragement, she could not bring herself to tell a boy to stop annoying her at school. Researchers also noted she began using them much later in the language acquisition process than most, as imperatives are usually among the earliest types of sentences young children form.

Genie seemed to view non-specific adjectives describing size, such as little, as absolute rather than relative values unless superlative or comparative markers were present. During a test using three different-sized objects, when asked to point to the "little" one she pointed to the medium-sized one, only pointing to the small one when Curtiss asked her to point to the "tiny" one. Similarly, when first asked to distinguish between all, some, and one, at first Genie would interpret some to mean all; by 1975, she had reversed this and began mistaking some for one instead, which Curtiss interpreted as a sign of progress. This contrasted with her ability to distinguish between more and less, which she had fully comprehended by at least August 1973. Although Genie understood and could freely use intensifiers such as the word very, until December 1972 she only tenuously grasped superlatives. She never used them in her own speech, but when listening to others she appeared to understand the suffix -est better than the word most. The contrast between her understanding and lack of production of superlatives furthered the researchers' belief that, even in the absence of language, her cognitive structure had developed in some form.

Until 1972, Genie responded to the conjunctions and and or as if they both meant and, but even after recognizing there was a difference never fully grasped the meaning of or. Even by 1977, Curtiss noted that Genie had never attempted to use any other conjunctions, such as but or if. Although she evidently grasped some prepositions, others, such as behind, over, and in front of, were less consistently understood; she frequently mistook both behind and in back of for in front of, though by 1977 her understanding of behind on tests had improved from 38.8% to 76.9%. Curtiss and Fromkin's 1974 papers also noted that by March 1973 Genie seemed unable to grasp on or under on one of their tests, even though she had been observed correctly using the word on in non-test settings. They suggested this disparity was likely due at least partially to logistical difficulties with the test, as she had to speak while moving objects into different positions; on subsequent preposition tests, she was not required to do this.

By December 1972, Genie understood and used the pronoun I, even pronouncing it with more stress for emphasis, but almost exclusively used it with either the word want or like. However, she interchangeably used you and me, and did not use any other pronouns. Curtiss said Genie would often say, "Mama love you" while pointing to herself, attributing this to Genie's inability to distinguish who she was from who someone else was. In addition, she never gained any use of pronomials in her speech. In 1973 and 1974, Curtiss tested Genie on possessive pronouns, such as his, your, and my, by asking her to point to different body parts on a picture of a boy and a girl. On these tests, Genie's responses were correct less than 50% of the time. By 1973, however, she began to use the possessive pronoun my, for instance, "Willie slap my face". On tests administered between 1972 and early 1974, she was shown pictures of children either being fed or eating, and had to identify the correct picture from the description; when given two sentences with reflexive pronouns, "The boy is feeding himself" or, "He is feeding himself" she got more wrong than right, but she did somewhat better when responding to the sentences with object pronouns, "He is feeding him" and, "He is feeding her."

Interrogative questions

In everyday interactions, Genie clearly understood and appropriately acted on most questions using interrogative words by February 1972; unlike most children who grasp who, what, which, and where questions much earlier than when, how, or why, the only one which took longer for Genie understand was why, and even this took considerably less time than was expected. Researchers speculated this was because, while answers to these questions all contain the same grammatical structures, the latter group of questions require more sophistication to properly answer. This helped to prove to the scientists that Genie's cognition was at a higher level than most children in that phase of language acquisition. Despite appropriate responses to these questions in non-test settings, Curtiss found Genie almost completely unable to respond when asked simple test questions such as, "Who is the girl pulling?" or, "What is the red box on?" Curtiss could not discern a method to Genie's verbal responses, and after seeing how much trouble it gave Genie decided to stop administering this test.

In addition to difficulty on comprehension tests, Genie did not ask questions with any grammatical markers in her speech and was completely unable to use interrogative questions. In February 1973, Curtiss and Fromkin thought Genie might be more successful with forming them in writing and had her arrange cards with words written on them; after several attempts, Genie formed, "What is under the green box?". This proved to be an isolated instance; Curtiss did not note Genie replicating this success with the word cards, and Genie remained entirely unable to ask an interrogative question while talking. She would only attempt to form them if requested, and two of her typical efforts were, "What red blue is in?" and, "Where is tomorrow, Mrs. L?" For a long time, her verbal responses to these questions were similarly ungrammatical. Curtiss attempted to help Genie memorize a few interrogative questions, which also did not work; for instance, in late May 1974 when Curtiss asked Genie to repeat, "Where are the graham crackers?", Genie responded with, "I where is graham cracker" or, "I where is graham cracker on top shelf." This inability was extremely unusual for a first-language learner, as children typically learn to use questions as they begin understanding them and typically ask interrogatives in their earliest two-word sentences. In addition, it starkly contrasted with her ability to learn other ritualized speech. Curtiss theorized Genie's difficulty was likely due to the linguistic movement interrogatives require, and in 1975 scientists speculated emotional difficulties may have made her unwilling to attempt forming them in spontaneous speech.

1974–mid-1975: Later testing

By 1974, after almost four years of language acquisition, Genie's ability to understand and use vocabulary remained considerably ahead of her grammar. In early 1974 the scientists estimated her grammar was congruous with that of a typical two or two and a half year old, although her verbal expressiveness was markedly lower, and they compared Genie's speech to that of teenagers and adults who had undergone a left hemispherectomy. The content of her speech was comparable to these hemispherectomy patients, although some individual components remained different. The scientists wrote that Genie was rapidly approaching the maximum extent of grammar acquisition observed in these hemispherectomy patients, but noted these patients had an advantage over Genie because, unlike Genie, their right hemispheres had already acquired at least a small amount of basic language. Nevertheless, their papers indicated that Genie continued to acquire grammar and vocabulary, and they also noted that she had far outstripped the other reported cases of similarly delayed language acquisition. At that time, they speculated she may have been able to indefinitely continue.

Genie's spontaneous utterances were now frequently longer and more complex, but how much was attributable to grammar acquisition versus rote memory was not readily obvious. Curtiss noted that, despite Genie's right-hemisphere brain dominance and the use of her right hemisphere for language, she still did not use the parts of language which are typically either bilateral or originate in the right hemisphere. In early 1974, Curtiss tested Genie on simple past tense sentences such as, "The girl opened the umbrella" and found that Genie was only correct 50% of the time. At around the same time, Curtiss began testing Genie's ability to distinguish between the active and passive voice and found she was completely unable to draw the distinction, as exemplified in her random responses to sentences such as, "The boy is pulling the girl" and, "The girl is being pulled by the boy". In her spontaneous speech, she never gained any use of the passive voice. This starkly contrasted with the findings of linguist and psychologist Thomas Bever, who had tested young children on reversible active/passive sentences similar to those Curtiss used to test Genie. He found that while most young children correctly respond at a chance level to passive sentences, their responses to the active voice are accurate about 95% of the time; this meant that, unlike Genie, young children usually knew the difference between familiar and unfamiliar constructions.

In May 1974 Curtiss recorded the first instances of Genie using compound noun phrases, which were the only times Genie would use the one conjunction she knew, and. At the same time, Curtiss noted her first compound sentences, such as, "Mama not have baby. Baby grow up." By the summer of that year, Genie was beginning to include indirect objects in her sentences, such as, "Curtiss give me valentine". She was also beginning to use more determiners in her sentences, and although largely still using them imitation she would spontaneously use another. She also began to use the benefactive case for the first time, although she did not always include the word for. In the fall of 1974 she began to use negatives embedded in sentences, first in imitation and spontaneously by October, and by the end of 1974 she had completely mastered this ability. She also gradually began using language to describe fictional events, attempting on at least two occasions in the last two years of her stay with the Riglers to lie to Marilyn.

Although Genie understood complex negation by this time, she only grasped certain complex sentences involving relative clauses. By early 1975 she showed comprehension of sentences where the object was the relative clause, such as "The boy is looking at the girl who is frowning", or sentences where the subject was the relative clause and did not end in a noun phrase, such as "The boy who is frowning is looking at the girl". However, when interpreting a sentence in which a relative clause ending in a noun phrase came before the main verb, such as "The boy who is looking at the girl is frowning", she interpreted the noun closest to the verb as the subject. This meant she was using a word order strategy, which the scientists considered progress.

Genie clearly understood the concept of temporality, and on early tests with sentences containing the words before or after she could correctly respond to sentences such as, "Touch your nose before your ear" or, "After you touch your ear, touch your nose." Later she could not only produce spontaneous sentences with temporal terms but could use conditional sentences to indicate causation, albeit without saying if–then; for instance, Curtiss recorded one utterance, "Neal not come, happy. Neal come, sad." However, by 1975 she remained largely unable to respond to sentences where the nouns were not in the same sequence as the events, such as "Touch your ear after you touch your nose", although she was showing more improvement with these sentences when asked to do something after instead of doing something before. She still made no distinction between the words here and there; on multiple tests, when told to come or go to a person or area she always gave identical responses to the instructions, responding to both, "Come here" or, "Go there" by going to to the closest person or area. By contrast, she demonstrated full comprehension of many other paired words, such as long and short or high and low. For some paired words, such as left and right, her answers on tests were still less than 100% even by 1977, but she consistently showed the same level of understanding for both words.

Through the first half of 1975, Genie had begun to use more than one prepositional phrase in some of her sentences. By this time, she had begun to differentiate between third-person pronouns such as he and she, but on pronoun tests still had a high rate of error. Genie understood self as a marker of reflexive pronouns, and was able to understand them in most scenarios. The one exception was when she encountered a noun phrase with a pronoun she misunderstood; for instance, if given the sentence, "He is feeding himself", she frequently confused he with she and therefore change himself to herself. She also showed full comprehension of the reciprocal each other. By contrast, she was still unable to fully understand object pronouns. Her pronoun acquisition was described at that time as "painfully slow", and she still did not use any pronouns besides I in her speech, but researchers insisted there was definite progress.

Furthermore, despite mastering word order Genie still had difficulty with distinguishing between simple actor–action–object sentences. In 1975, when given the sentences "The girl pulls the boy" or "The boy pulls the girl" and asked to point to the corresponding picture, her answers would either be all correct or all incorrect. While this was progress from 1971 and 1972, when she simply guessed, this indicated that she was attempting to use a word order strategy but could not ascertain a specific formula. Her difficulty with this also manifested itself in her inability to use word order to tell the difference between sentences such as, "What is on the blue box?" and, "What is the blue box on?". In addition to the disparity with the results on pronoun and relative clause tests, which indicated Genie was using word order strategies, researchers wrote this was a major contrast with the clearly defined word order rules observed in Genie's spontaneous speech.

Auxiliary structure

Genie's speech had also remained entirely devoid of pro-forms, modal verbs, or auxiliary verbs such as have or will, although by 1974 she could imitate the individual words to some degree. One test consisted of six sets of three pictures, and each set contained depictions of an action which had occurred, was occurring, or was about to occur. From October 1973, when researchers first conducted this test, to January 1974, she was perfect at identifying past tense sentences such as, "The girl finished opening the umbrella". When asked to identify pictures with the future tense she was almost perfect if the sentence was phrased with going to, but showed no comprehension when Curtiss asked her to identify sentences with the same meaning but using the auxiliary verb will. This was in stark contrast to most children, who almost always correctly respond to both. The scientists wrote her lack of comprehension or use of auxiliary structures, despite understanding identical messages phrased with inflected words, was consistent with her ability to grasp conceptual information far better than grammar.

By early 1975, Genie had started including do-support in some of her sentences; for instance, in June 1975 she said, "I do not have a red pail".This was the only use of any auxiliary structure in her speech, but even this was only used with the word I. This caused Curtiss to speculate that Genie had memorized "I do" as an independent phrase as opposed to using "do" as a separate auxiliary word. Even then, it was often incorrectly used, as in sentences such as, "I did not sad" (Curtiss said this had meant, "I am not sad", and noted it was also from June 1975), and still frequently omitted. She was also not observed using any contractions, either for negations or anything else, in her speech. Similarly, it was not until January 1974 that scientists noticed the first instances of her using copulas in her spontaneous sentences.

Conversational abilities

Despite Genie's readily apparent desire for attention and socialization, she never learned to use automatic speech. Genie could start and continue a conversation on a topic, but even after her vocabulary had expanded, she continued to rely on repeating words or short phrases to maintain the discussion. Researchers noted that when asked a yes or no question, Genie would say no even if she meant yes and was shaking her head the correct way. They thought Genie was simply repeating the last word of a sentence, causing Curtiss to design a test to ensure Genie actually understood yes and no. What grammar rules and syntax she did know were inconsistently applied; for instance, even after learning and demonstrating use of past tense, she did not normally use it in everyday conversations. In these situations, she would only use the correct markers if separately, specifically asked about tense. In everyday conversations, she frequently understood and could respond to highly complex questions; once, when someone asked Genie, "Do you want me to play the piano for you for a little bit?", Genie answered, "Long time." However, her comprehension of other complex sentence structures remained inconsistent, although beginning in November 1973 researchers noted slow, noticeable improvement. Because describing past events requires using multiple tenses, what would normally be very simple descriptions proved extremely difficult.

Speech progress

When Genie first began speaking, her speech was very soft and completely monotonic. Her voice was extremely high-pitched—a trait which scientists had observed in earlier cases of feral children—and at first it was so high that it did not register on the instruments researchers used to acoustically analyze her speech. Some of her earliest imitations were almost completely silent, and many others sounded were so soft they sounded like whispers. Over time, her voice gradually lowered in pitch and became somewhat louder, but her voice was still very high-pitched and her pronunciation stayed soft and breathy. Like most children she clearly understood different tones of voice, and over time her voice became slightly more varied, but her voice remained mostly monotonic even after she began speaking in longer sentences. Even in 1977, she could not use intonation to indicate a question. This was extremely unusual, as most children learning a first language thoroughly master stress and pitch modulation even before learning any individual words, and can normally use a wide variety of pitches and intonations even during their babbling phase.

In addition to emotional problems affecting Genie's early speech output, scientists noted that physical factors inhibited Genie's ability to speak. When she was first removed from captivity, the muscles used to produce speech were severely atrophied. Whereas most people learn to use their respiratory system to produce speech sounds as babies, as they learn to control breathing, Genie had been forced to repress all vocalization from a very early age. This meant her larynx and vocal tract were extremely underused, which made it difficult to control both air flow and her vocal chords. Even as late as 1975, although there was marked improvement she still had considerable difficulty with physical speech production; when she attempted to modulate the pitch of her voice, her entire body frequently stiffened from effort and concentration. This was at least part of the reason her voice was so quiet and devoid of intonation, as changing both pitch and volume requires the ability to freely use the necessary muscles, and scientists wrote this was likely the reason her voice was so high-pitched.

Genie's speech was marked by both consonant and vowel reduction, vowel neutralization and deletion, and reduction of many consonant clusters. Similar to young children, most of her first words were monosyllabic and consisted of consonant-vowel-(consonant) sequences; the consonants were usually a labial or dental stop, and the vowels were monophthongs. But while most children's first disyllabic words also follow this pattern, hers had both consonant-vowel and vowel-consonant sequences. When she first started speaking, the only consonant clusters she would pronounce were clusters with a consonant followed by a liquid consonant. She frequently substituted vowels, with considerably more variation than she would consonants, and although it was not random she did not seem to draw distinctions based on normal classification such as front versus back or open versus close vowels. As she did not have enough control of her voice to produce normal stress patterns, to indicate a stressed syllable she would instead hold out the sound longer. Even when she began using longer words and sentences she often deleted unstressed syllables, but would sometimes include a schwa where the deleted sound would have been; Curtiss thought Genie invented a grammar rule allowing her to either delete or reduce these vowels.

In normal speech Genie would frequently, but not always, delete the final consonant; the scientists speculated that, according to her grammar, the final consonant was optional. Researchers suspected the reason Genie did not usually use plural forms, possessive markers, and past tense or third person singular conjugations, despite her apparent ability to both comprehend and use them, was her frequent final consonant deletion. When the last sound was a nasal consonant, she would inconsistently pronounce it; if she did not pronounce it she either nasalized the preceding vowel or changed the consonant to a non-nasal, but never both. However, if someone imitated her deletion of a final consonant she would laugh, reply, "Silly", gesture, and then produce the word with both the final consonant and any sounds she had deleted in her initial pronunciation. When she used voiceless stops to start a word, they were aspirated or unaspirated seemingly at random; the one exception to this was that the stop in an s-stop consonant cluster was always unaspirated. Early on, she would regularly substitute the /t/ sound with a /k/, /n/, or /s/. For several months, in her syllabic structure she did not use the two affricates in Standard American English as initial consonants, and inconsistently used them as final consonants. In 1973, Genie began to use a epenthetic schwa sound to break up consonant clusters consisting of an initial C followed by a liquid consonant. By 1973, Genie had begun to articulate consonant clusters consisting of an /s/ sound followed by a nasal consonant. At the same time, in words starting with an /s/ followed by other types of consonant clusters, Genie started to break up the cluster with an epenthetic schwa; as reduced vowels in English are generally schwas, the scientists thought this may have been evidence that she was gaining command of English phonology. However, though she could produce all of the consonants in Standard American English by this time, she still did not use voiced or voiceless dental fricatives in spontaneous speech despite imitating them since June 1972.

Curtiss and Fromkin's later papers on Genie from this period noted that by 1973, she seemed to be slowly improving her articulation. Similar to children acquiring a first language, her enunciation remained far better in imitation than in her own utterances; the scientists observed her combining several sounds in imitation that she never spontaneously used. Although her voice was still largely monotonic, she began to utilize more speech patterns and intonation, although it remained better in imitation. To indicate stress she began raising the pitch of her voice in addition to holding the sound out longer, although she still did not do this to indicate either questions or imperative sentences. By 1974, the scientists wrote that although her speech remained behind her comprehension, her progress with both language and speech was occurring at the same rate. They further noted that Genie's substitution of /t/ sounds were now only occurring in medial consonants. In 1975 the scientists wrote that Genie was clearly showing stress patterns in all of her spontaneous speech, modifying both pitch and volume for emphasis. However, despite her obvious progress she would avoid speaking if possible, which the scientists thought was due to a combination of physical and emotional difficulties. The dichotomy between her phonetic comprehension and production also showed in her ability to identify words which rhyme; she had demonstrated this while playing with Curtiss in non-test settings, and when tested on it in 1975 she had no difficulty. This suggesting that her difficulty was with realization, as opposed to pronunciation. When she began using two and three-syllable words she pronounced them all with the correct stress patterns, and by early 1975 she began to show clear stress patterns by modifying both pitch and amplitude for emphasis. However, her stress patterns were still far less clear than those of most people, and producing them remained extremely laborious.

In the later years of Genie's stay with the Riglers, when she started trying to form longer sentences, she would typically only enunciate a few of the sounds; for instance, "Monday Curtiss come" would sound more like "Munk". She also frequently omitted syntactical elements which, though necessary to make sentences grammatical, would have been clear in context. Although this is normal in young children at the outset of language acquisition, the omissions normally decrease after acquisition of basic language structures; by contrast, even after Genie mastered some of these features, she continued to leave out many grammatical markers. In addition to making it difficult for most people unfamiliar with her speech to understand her, this made it hard to be completely certain what Genie’s true linguistic abilities were, and the scientists noted in their publications that her speech was not always a reliable indicator of Genie’s full capabilities. Curtiss attributed this to Genie trying to say the least she possibly could and still be understood, noting she would better articulate her speech when explicitly, firmly requested to. Upon observing this, linguists following the case began to call her the Great Abbreviator.

Recalling past events

Near Christmas 1971, a boy playing with a toy pistol at Children's Hospital frightened Genie. When Curtiss tried to reassure her, Genie responded with an abbreviated version of Curtiss' words, saying, "Little bad boy. Bad gun." About two weeks later, Curtiss heard Genie saying something to herself and using a gesture she had invented for the word "naughty"; when Curtiss asked Genie what she was saying, she repeated the words, "Little bad boy. Bad gun." out loud for several minutes, marking the first time she used language to refer to something in the past. Some months later, the Riglers overheard her saying, "Father hit big stick. Father is angry." to herself, demonstrating she could even talk about her life before learning language; this gave researchers new insights into her early life and disproved the theory of 18th century philosopher Étienne Bonnot de Condillac that humans require language to form memories. During the rest of her stay with the Riglers, they said she would constantly repeat "Father hit" to herself. Eventually, Genie could provide longer and more detailed memories of her past. The Riglers tried to get her to talk about her childhood as much as possible, and Marilyn would sometimes coach Genie by role-playing as Genie's real mother. Before the Riglers worked with Genie to understand the concept of death she often asked where her father was, afraid that he would come to get her. She gradually began to speak about her father, and could talk about his treatment of her.

"Father hit arm. Big wood. Genie cry...Not spit. Father. Hit face – spit. Father hit big stick. Father is angry. Father hit Genie big stick. Father take piece wood hit. Cry. Father make me cry. Father is dead."

Non-verbal communication

Even while speaking, Genie continued to use supplementary nonverbal gestures to improve her intelligibility. With some words, she would pantomime them as she spoke; for instance, the scientists noted she would crouch into a seated position when she said the words "sit" or "sick". Although this is normal to some degree among children learning a first language, she seemed to use them as an integral part of her vocabulary. As Genie had considerable difficulty with switching between tenses in her speech, which describing past occurrences requires, Curtiss said she would also act out events. When she was not understood right away, she would persist until her message was communicated. By 1974 Genie could read names and words, and could write individual letters in print. When Genie was first removed from confinement she would only draw pictures if asked to, but during her stay with the Riglers she began to use drawings if she could not express herself in words. Her sophisticated sense of perspective rapidly became evident in many of her drawings; by November 1971 she could depict silhouettes and figures in profile, both of which require a relatively high degree of ability.

In addition to her own drawings, Genie would frequently use pictures from magazines to relate to daily experiences. She especially collected pictures of things that frightened her; Curtiss recalled one incident when a helmeted diver scared Genie, after which she would not relax until she showed Curtiss a picture she had found of a similar looking diver in a National Geographic issue. Several months into Genie's stay with the Riglers, she found a picture of a wolf in a magazine which sent her into a terror. When the Riglers saw her reaction, they asked Genie's mother if she knew of something that might have caused it; it was then that she told them about how her husband had acted like a dog to intimidate Genie and keep her quiet, which was the first time the underlying reason for her fear became apparent to the scientists.

The Riglers and Curtiss saw how frequently and effectively Genie used her nonverbal skills, with Curtiss noting in particular how quickly Genie could organize very complex stories in her drawings. She still seemed to be able to communicate with complete strangers without speaking; David Rigler vividly remembered an occasion when he and Genie passed a father and a young boy carrying a toy firetruck without speaking to each other, and said the boy suddenly turned around and gave the firetruck to Genie. Although the scientists tried to get her to talk as much as possible, they knew one of the major flaws with Jean Marc Gaspard Itard's work with Victor of Aveyron was his insistence that Victor learn one method of communication—in his case writing—to the exclusion of others. They wanted to take full advantage of her ability to use gestures, so in 1974 the Riglers arranged for her to learn American Sign Language; Curtiss wrote that as soon as Genie started learning sign language, she would often simultaneously speak and sign. Even when learning sign language, Genie continued to use and invent her own gestures. Although the scientists did not test Genie's progress with sign language, Curtiss recorded that by the spring of 1975 Genie could correctly use the sign indicating past tense.

Impact

Genie's is one of the best-known cases of language acquisition in a child with delayed development. Since Curtiss published her findings, the vast majority of linguistic books have used Genie as a case study, frequently citing it as proof of Chomsky's theory of innate language and a modified version of Lenneberg's theory. In her writings, Curtiss argued for a weaker version of the critical period theory; that normal language acquisition cannot occur beyond puberty. She wrote that despite the innate ability of humans to acquire language, Genie demonstrated the necessity of early language stimulation in the left hemisphere of the brain to start, drawing a comparison to a baby who upon being born does not breathe until stimulated by a midwife. Furthermore, she stated that only language, not any other cognitive stimulation, could provide the necessary spark. Without the required stimulation, a person would be rendered incapable of processing language from the left hemisphere of the brain and would be forced to only use the right hemisphere, which is typically only used to process non-speech sounds. This did not mean the person would never be capable of producing any language, but that language would never progress into normal-sounding speech. Her arguments have become widely accepted in the field of linguistics, and were the impetus for several additional studies.

In particular, analysis of the data collected from Genie showed a sharp contrast between a linguistic and grammatical component in language. Although Genie acquired vocabulary well above the level of her estimated mental age, she never mastered phonology or a substantial amount of grammar. It was already known that adults who underwent a left hemispherectomy were better at regaining and maintaining vocabulary than grammar and syntax, similar to Genie; both the observations by Curtiss and the tests conducted on Genie's brain further bolstered the theory that the two processes underwent separate development. Scientists also noted the grammatical skills Genie acquired and used bore striking resemblance to both the grammar and syntax of pidgin languages and the gesture systems deaf children invent when isolated from other deaf people. While both of these contain certain aspects of language, such as vocabulary, recursion, and word order, other components such as auxiliary structures are never present. Prior to Genie's discovery, the auxiliary component of language had been known to be one of the few acquired at different rates by children depending on the amount of language they heard. Genie's inability to master these structures supported the idea that the development of auxiliary and other similar syntactical systems is more sensitive than vocabulary, requiring a more conducive language environment to properly develop with a more specific critical period. This also suggested there was a separation of cognition and language rules, a new concept at the time. Genie's spatial and nonverbal skills were exceptionally good, which demonstrated that even nonverbal communication was fundamentally separate from actual language.

Genie's case has also been used in theorizing about whether the critical period hypothesis can be applied to the acquisition of a second language, a topic which remains the subject of considerable debate.

Debate

The extent of Genie's linguistic abilities has been the subject of some debate. Curtiss' earlier writings, up to and including her 1977 dissertation, appear very optimistic. As early as 1972 she indicated that, although Genie was progressing more slowly than most children acquiring language, there was strong evidence she was very gradually incorporating more basic grammar into her speech and that she was building on those skills. All of her papers leading up to her dissertation discussed specific improvements in Genie's lexical and grammatical abilities, and argued that although her acquisition of the latter was often significantly slower it was clearly occurring. In her dissertation, she argued that while Genie's speech was still considerably different from that of most people, her, "language performance often does not reflect her underlying linguistic ability". Although she rarely used grammatical rules such as pluralization, it was clear she understood and had the ability to use them. Curtiss further wrote that Genie was still in the process of learning language and thought she might complete acquisition; in her dissertation, Curtiss expressed hope that, "[Genie] will have the last word."

The first papers Curtiss wrote on the subject after her dissertation noted a severe regression in Genie's speech from the trauma she suffered after entering her first foster home in 1975, but she argued that Genie's utterances had always been, "grammatically uninflected and telegraphic", claiming many of them were completely incomprehensible (in subsequent papers, she used the word agrammatic instead of telegraphic). These later writings acknowledged that Genie clearly understood word order, used most verbs within their constraints (for instance, she had said, "Genie throw ball" but never, "Genie throw"), showed some signs of feature specification, and could correctly use what bound morphemes she knew. However, they all had more negative evaluations of Genie's speech, arguing that while Genie's vocabulary had steadily broadened she had never learned any meaningful amount of grammar or morphology after all. In a 1992 interview with Russ Rymer Curtiss said Genie's progress had very quickly plateaued and it took her several years to realize it, and in a 1993 interview with Nova she said that Genie communicated messages but did not speak in real sentences; she cited two of Genie's utterances as examples, "Spot chew glove" and, "Applesauce buy store". An independent 2006 review of Genie's case concluded that Curtiss' dissertation was overly optimistic about Genie's progress and prognosis; it pointed out that even by its completion, Genie had clearly regressed from her treatment in foster care.

However, a 1995 analysis in a paper by Peter Jones, a linguistics professor at Sheffield Hallam University, argued that earlier accounts of Genie's speech, especially of her progress during the period between 1970 and 1975, were more accurate than those produced after 1977. This analysis argued that Curtiss used only small samples of Genie's speech to prove her points, when a more representative look appeared to contradict Curtiss' arguments. For instance, whereas in 1981 Curtiss had pointed to 13 of Genie's utterances to demonstrate a lack of grammar acquisition, Jones argued these were mostly undated and that Curtiss did not show these were typical of Genie's speech. Jones also examined a selection of Genie's utterances Curtiss used in her later papers to indicate a lack of any hierarchical depth in her speech, arguing that while they were not representative of a typical speaker they had a hierarchic structure to at least some degree. In a few instances, Jones asserted that data Curtiss used in her later arguments outright contradicted her conclusions.

While Jones acknowledged Genie's regression after mid-1975, he argued that Curtiss did not release enough information about Genie's speech between 1975 and 1977 and that there was no data from any time after January 1978, rendering it impossible to draw definitive conclusions on how far she regressed and what, if any, grammatical skills she had lost. He further noted that despite this regression, in 1977 Curtiss wrote that Genie clearly acquired and was acquiring some grammar and syntax. Finally, Jones wrote that in her interview with Rymer she supplied no evidence to back up her statement, and pointed out that the two utterances referenced in the Nova documentary were from early December 1971 and April 1972 respectively, which were not representative of Genie's most advanced speech. Further, he argued that she wrote nothing to this effect in her dissertation, and had never suggested reevaluation of her earlier arguments nor disavowal of her earlier conclusions. These factors, Jones concluded, demonstrated that, "the post-(1977) account [of Genie's speech] is not so much based on reanalysis or reinterpretation of the data but on a highly selective and misleading misrepresentation of the earlier findings."[emphasis as in the original] This, in turn, left an unresolved tension between Curtiss' pre- and post-1977 analyses which he said meant, "a definitive judgment on the character and extent of Genie's linguistic development still cannot be given." Others discussing Genie's case have since cited these arguments. To this point, neither Curtiss nor anyone else directly associated with Genie has responded to Jones' paper.

Sources and further reading

• Aitchison, Jean (1989), The Articulate Mammal: An Introduction to Psycholinguistics (3 ed.), New York, NY: Routledge, ISBN 978-0-41-508395-9, OCLC 802910308.
• Benzaquén, Adriana Sylvia (2006), "Confinement and Freedom", Encounters with Wild Children: Temptation and Disappointment in the Study of Human Nature, Montreal, Quebec: McGill-Queen's University Press, pp. 244–264, ISBN 978-0-77-352972-4, OCLC 61427587.
• Bickerton, Derek (1990), "The Fossils of Language", Language and Species, Chicago, IL: University of Chicago Press, ISBN 978-0-22-604610-5, OCLC 802686883 {{citation}}: External link in |chapterurl= (help); Unknown parameter |chapterurl= ignored (|chapter-url= suggested) (help).
• Curtiss, Susan (1977), Genie: A Psycholinguistic Study of a Modern-Day "Wild Child", Boston, MA: Academic Press, ISBN 978-0-12-196350-7, OCLC 3073433.
• Curtiss, Susan (1982), "Developmental dissociations of language and cognition", in Obler, Loraine K.; Menn, Lise (eds.), Exceptional Language and Linguistics (PDF), New York, NY: Academic Press, pp. 285–312, doi:10.1017/S0022226700010197, ISBN 978-0-12-523680-5, OCLC 8410214, archived from the original (PDF) on May 29, 2013, retrieved May 1, 2013 {{citation}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help).
• Curtiss, Susan (1988), "The special talent of grammar acquisition", in Obler, Loraine K.; Fein, Deborah (eds.), The Exceptional Brain: Neuropsychology of Talent and Special Abilities (PDF), Guilford, NY: Guilford Press, pp. 364–386, ISBN 978-0-89-862701-5, OCLC 14719594, archived from the original (PDF) on May 29, 2013, retrieved May 2, 2013 {{citation}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help).
• Curtiss, Susan (1988), "Abnormal language acquisition and the modularity of language", in Newmeyer, Frederick J. (ed.), Linguistics: The Cambridge Survey: Volume 2, Linguistic Theory: Extensions and Implications (PDF), vol. 2, New York, NY: Cambridge University Press, pp. 96–116, doi:10.1016/0013-4694(86)90177-X, ISBN 978-0-51-162105-5, OCLC 18836853, archived from the original (PDF) on May 29, 2013, retrieved May 1, 2013 {{citation}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help).
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• Grinstead, John; MacSwan, Jeff; Curtiss, Susan; Gelman, Rochel (1998), "The Independence of Language and Number", in Greenman, Annabel; Hughes, Mary; Littlefield, Heather; Walsh, Hugh (eds.), Proceedings of the Annual Boston University Conference on Language Development (PDF), vol. 22, Somerville, MA: Cascadilla Press, pp. 303–313, ISBN 978-1-57-473032-6, OCLC 39374675, archived from the original (PDF) on December 28, 2005, retrieved February 5, 2013 {{citation}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help); Unknown parameter |displayeditors= ignored (|display-editors= suggested) (help); Unknown parameter |month= ignored (help).
• Krashen, Stephen D.; Curtiss, Susan; Fromkin, Victoria A.; Rigler, David; Rigler, Marilyn (1974), "Lateralization in the case of Genie", Cerebral dominance: Proceedings of the Workshop Conference of the Fourth International Congress of Psychoneuroendocrinology, University of California, Los Angeles January 5, 1973 (PDF), Los Angeles, CA: Brain Information Service/BRI Publications Office, pp. 13–14, OCLC 1079136, archived from the original (PDF) on May 29, 2013, retrieved May 21, 2013 {{citation}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help).
• Newton, Michael (2002), "Where is Tomorrow, Mrs L.?", Savage Girls and Wild Boys, New York, NY: Macmillan, pp. 208–247, ISBN 978-0-31-242335-3, OCLC 54696995.
• Pinker, Steven (2007), "Baby Born Talking—Describes Heaven", [[The Language Instinct| The Language Instinct: How The Mind Creates Language]] (3 ed.), New York, NY: HarperCollins, pp. 296–302, ISBN 978-0-06-095833-6, OCLC 263595357 {{citation}}: URL–wikilink conflict (help).
• Reynolds, Cecil R.; Fletcher-Janzen, Elaine, eds. (2004), Concise Encyclopedia of Special Education : A Reference for the Education of the Handicapped and Other Exceptional Children and Adults (2 ed.), Hoboken, NJ: John Wiley & Sons, pp. 428–429, ISBN 978-0-471-65251-9, OCLC 46975017.
• Rymer, Russ (1993), Genie: a Scientific Tragedy, New York, NY: Harper Perennial, ISBN 978-0-06-092465-2, OCLC 29616957.
• Sampson, Geoffrey (1997), "The original arguments for a language instinct", Educating Eve: The 'Language Instinct' Debate, London, UK: Continuum Publishing, pp. 23–64, ISBN 978-0-30-433908-2, OCLC 490496141.
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• Yamada, Jeni Ellen (1990), Laura: A Case for the Modularity of Language, Boston, MA: A Bradford Book, ISBN 978-0-26-224030-7, OCLC 21760166.