||This article needs attention from an expert on the subject. (February 2012)|
Cat intelligence is the capacity of the domesticated cat to learn, solve problems, and adapt to its environment. Research[which?] has also shown feline intelligence to include the ability to acquire new behavior that applies previously learned knowledge to new situations, communicating needs and desires within a social group, and responding to training cues.
- 1 Brain
- 2 Intelligence
- 3 Memory
- 4 Domestication effect
- 5 Artificial intelligence
- 6 See also
- 7 References
- 8 Further reading
- 9 External links
The brain of the domesticated cat is about 5 centimetres (2.0 inches) long and weighs 25–30 g (0.88–1.06 oz). If a typical cat is taken to be 60 cm (24 in) long with a weight of 3.3 kg (7.3 lb), then the brain would be at 0.90% (0.91%) of its total body mass, compared to 2.00% (2.33%) of total body mass in the average human. Within the encephalization quotient proposed by Jerison in 1973, values above 1 are classified big brained, lower than 1 are small brained. The domestic cat is attributed a value of between 1 – 1.71 relative to human value that is 7.44 – 7.8. The largest brain in the cat kingdom are those of the tigers in Java and Bali, of which the largest relative brain size within the pantera is the tigris. It is debated whether there exists a causal relationship between brain size and intelligence in vertebrates. Correlations have been shown between these factors in a number[quantify] of experiments.[which?] However, correlation does not imply causation. Most experiments involving the relevance of brain size to intelligence hinge on the assumption that complex behavior requires a complex (and therefore intelligent) brain; however, this connection has not been consistently demonstrated.
The surface area of a cat's cerebral cortex is approximately 83 cm² whereas the human brain has a surface area of about 2500 cm². Furthermore, a theoretical cat weighing 3,500 grams has a cerebellum weighing 5.3 grams, 0.17% of the total weight.
According to researchers at Tufts University School of Veterinary Medicine, the physical structure of the brains of humans and cats are very similar. The human brain and the cat brain both have cerebral cortices with similar lobes.
The number of cortical neurons contained in the brain of the cat is reported to be 763 million. Area 17 of the visual cortex was found to contain about 51,400 neurons per mm3. Both human and feline brains are gyrencephalic, i.e. they have a surface folding.
Analyses of cat brains have shown they are divided into many areas with specialized tasks that are extremely interconnected and share sensory information in a kind of hub-and-spoke network, with a large number of specialized hubs and many alternate paths between them. This exchange of sensory information allows the brain to construct a complex perception of the real world and to react to and manipulate its environment.
The thalamus of the cat constituting a hypothalamus, epithalamus, ventral and dorsal parts and including a lateral geniculate nucleus, and additional secondary nuclear structures are responsible for controlling impulses to the cortex, functions of sleep, memory originally formed of sensory datum, and cellular functioning otherwise unknown, as yet not fully understood (unnaccounted for). The thalamus has neuronal connectivity to the cerebellum.
Grouse et al. 1979 ascertained the neuroplasticity of kittens' brains, with respect to control of visual stimulus correlated with changes in RNA structures. In a later study, it was found that cats possess visual-recognition memory, and have flexibility of cerebral encoding from visual information, adaptability corresponding to changing environmental stimuli.
Secondary brain structures
The domestic cat brain also contains the hippocampus, amygdala, frontal lobes (which comprise 3 to 3.5% of the total brain in cats compared to about 25% in humans), corpus callosum, anterior commisure, pineal gland, caudate nucleus, septal nuclei and midbrain.
Brain and diet
||This section possibly contains original research. (June 2013)|
For the optimum health and functioning of the brain, a cat would require primarily manganese, potassium, Vitamin D, Vitamin B1, and Vitamin B6. Calcium, sodium, magnesium, and Vitamin A should be provided as part of a nutritionally balanced diet. Additionally, taurine is an essential amino acid in a cat's diet: taurine insufficiency leads to retinal degeneration and blindness in cats.
Intelligence through behavioural observation is defined as a composite of skills and abilities. The WAIS test is a measure of intelligence in adult homo sapiens. The test scores on four criteria; verbal comprehension, perceptual organisation, working memory and processing speed. In a comparative evaluation from WAIS criteria, cats are generally fair in intelligence. The working memory of the domesticated cat is surmised from experiment as being 16 hours.
Factors that contribute to greater intelligence are the velocity at which electrical transmission is conducted and with the greater number of cortical neurons. Compared to mammalian species this number was eleven-fourteenth in total.
Experimental results seemed to indicate that cats have no capacity for object permanence, as defined through investigation by J. Piaget with infants. Further research made to identify a similar factor of cognition showed behaviour indicative of object permanence cognition, although of a different type to that identified initially by Piaget. Further research showed that the animal has an awareness of objects not directly available to sight, and also sensory-motor intelligence comparable with a two-year old child. In experimental conditions, the memory of a cat was demonstrated as having an information-retention or recall, of a duration totaling as much as 10 years.
Taken as a whole, cats have excellent memories. However, relationships with humans, individual differences in intelligence, and age may affect memory. Cats adapt to the environment that they are in easily because they can recall what they have learned in the past and adapt these memories to the current situation to protect themselves throughout their lives.
For kittens, play is more than simple enjoyment and fun in the animal world. These things rank social order and prey-capturing skills and hone the cat for survival. In addition to this, they are exercising their minds and bodies in rehearsal for their adult roles. Before they were domesticated, kittens learned survival skills such as where to find food from observing their mothers. The first two to seven weeks are a critical time for kittens. This is when they bond with other cats. Without any human contact during this time, the cat would forever mistrust humans, according to some experts.[who?]
Just as in humans, advancing age may affect memory in cats. Some cats may experience a weakening of both learning ability and memory that affects them adversely in ways similar to those occurring in poorly aging humans. A slowing of function is normal, and this includes memory. Aging may affect memory by changing the way their brain stores information and by making it harder to recall stored information. Cats lose brain cells as they age, just as humans do. The older the cat, the more these changes can affect its memory. There have been no studies done on the memories of aging cats and memory, but there is some speculation[by whom?] that, just like people, short term memory is more affected by aging. However, research says that adult cats have a memory span of 16 hours compared to only 5 hours in adult dogs especially when it benefits the cat directly.
Diseases may affect memory
Disease may also affect cat memory. There is a syndrome called Feline Cognitive Dysfunction (FCD) that is similar to Alzheimer's disease in humans. The symptoms include disorientation, reduced social interaction, sleep disturbances, and loss of house training. This syndrome causes degenerative changes in the brain that are the source of the functional impairment.
Cat intelligence study is mostly from consideration of the domesticated cat. The process of domestication has allowed for closer observation of cat behaviour and in the increased incidence of interspecies communication, the inherent plasticity of the cat's brain has become apparent as the number of studies in this have increased scientific insight. Changes in the genetic structure of a number of cats has been identified as a consequence of both domestication practises and the activity of breeding, so that the species has undergone genetic evolutionary change due to human selection. The domesticated cat developed by artificial selection to possess characteristics desirable for the sharing of human habitation and living, coupled with an initial naturally occurring selective set of cat-choices made while interacting with Neolithic urban environments.
The intelligence of the cat is believed to be largely dependent upon its inter-species relations, e.g. between H. sapiens and F. catus, and is reflected in responses in the stress hormones released in cats kept from exploratative behaviours. That is to say, an enriched and stimulating environment produced by exploring urban places increased the likelihood of cerebral plasticity due to the need of situations requiring novel adaptive behaviours. This scavenging behaviour would only have produced slow changes in evolutionary terms. Such changes are comparable to the changes to the brain of early primitive hominids who co-existed with primitive cats, like Machairodontinae, Megantereon and Homotherium, and adapted to savannah conditions.
Considering the fossil-based family tree of placental mammals above; the feline line diverged many years previously from the primate line; the cat both feral and domesticated is likely to be maintained in a stasis by its niche position in the current food web.
The cats in the key experiments conducted by Edward Thorndike were able to learn through operant conditioning. In Thorndike's experiment, cats were placed in various boxes approximately 20 inches long, 15 inches wide, and 12 inches tall with a door opened by pulling a weight attached to it. The cats were observed to free themselves from the boxes by "trial and error with accidental success." In one test the cat was shown to have done worse in a later trial than in an earlier one, suggesting that no learning from the previous trials was retained in long-term memory. The scientist considered the cat to have the capacity for learning due to the law of effect, which states that responses followed by satisfaction (i.e. a reward) become more likely responses to the same stimulus in the future.
An experiment was conducted in 2009 where cats could pull on a string to retrieve a treat under a plastic screen. When presented with one string, cats had no trouble getting the treats. When presented with multiple strings, some of which were not connected to treats, the cats were unable to consistently choose the correct strings, leading to the conclusion that cats do not understand cause and effect in the same way that humans do. Thorndike was skeptical of the presence of intelligence in cats, criticising sources of the contemporary writing of the sentience of animals as "partiality in deductions from facts and more especially in the choice of facts for investigation."
Research was made to identify possible observational learning in kittens. Kittens that were able to observe their mothers performing an experimentally organised act were able to perform the same act sooner than kittens that had observed a non-related adult cat, and sooner than the ones who, being placed in trial and error conditions, observed no other cat performing the act. Experimental investigation of primates show that the chimpanzee possess some limited insight in regard to observational learning (see Köhler), whereas this capacity is wholly absent in the domesticated cat,[clarification needed] P. leo, and P. tigris.
The effect of training
Cats are known to be trained as circus animals, although traditionally considered difficult mainly because they appear to assume such behaviors only in exchange for a direct benefit. A good example of this is The Yuri Kuklachev Cat Theatre based in Moscow, the owner of which has been training cats for many years to do a full range of circus-style tricks. Also there is the belief that cats are difficult to train owing to impatience and boredom with the training exercise.
In assessing the limitations resulting from the genetic propensity that the cat as a species has for adaption to a more intelligent biological state through evolutionary means, animal integrity is cited a reason that genetic transformation of animals should not proceed.
In considering the unlikely likelihood of the cat developing intelligence should the opportunity for longitudinal evolutionary changes occur, e.g. if humanity becomes extinct, the likelihood of an evolution of pantera intelligence within the millions-of-years time-scale identified by the evolution of human intelligence studies is a factor of genetics.
Since 2006, when the entire DNA constituents in sequence of the Abyssinian cat were made into a genetic map of the Felis catus, genetically engineering some form of enhanced cat intelligence has become theoretically possible, although it is presently unlikely to ever be created due to ethical restrictions as well as practical considerations. Artificially enhanced cat intelligence would therefore only become a consideration for use in experiment, perhaps at some unknown time in future. The production of more intelligent cats might be theoretically a consideration for military organisations i.e. DARPA, in the hope of gleaning some advancement in warfare. Practically the common cat has proved little use for military personnel (Acoustic Kitty), despite the potential inherent in a creature with far greater prowess and agility than any human.
In November 2009, scientists simulated a cat's brain using a supercomputer containing 24,576 processors. This experiment did not simulate the function of the individual neurons in the brain, nor their synaptic patterns. It was intended to demonstrate that the problem of simulating a biological brain could be scaled to very large supercomputer platforms.
There are a number of reasons the cat brain is a goal of computer simulations. Cats are familiar and easily-kept animals, so the physiology of cats has been particularly well studied. The physical structures of human brains and cat brains are very similar. Cats, like humans, have binocular vision that gives them depth perception. Building artificial mammal brains requires ever more powerful computers as the brain gets more complex, from the mouse brain, to the rat brain (in 2007), to the cat brain, and ultimately to the human brain. Building artificial mammal brains advances the research of both neuroscience and artificial intelligence, but also leads to questions of the definition of sentient and conscious life forms, and to the ethics of artificial consciousness and the ethics of artificial intelligence.
- Roth, Gerhard; Dicke, Ursula (2005). "Evolution of the brain and intelligence". Trends in Cognitive Sciences 9 (5): 250–7. doi:10.1016/j.tics.2005.03.005. PMID 15866152.
- Kinser, Patricia Anne. "Brain and Body Size". Serendip. Bryn Mawr College. Retrieved 26 June 2013.
- Freberg, Laura (2009). "Relative Encephalization Quotients". Discovering Biological Psychology. p. 56. ISBN 978-0-547-17779-3.
- Deamer, Dave (5 November 2009). "Calculating Animal Intelligence".[self-published source?]
- Davies, Paul (2010). "How Much Intelligence is Out There?". The Eerie Silence: Renewing Our Search for Alien Intelligence. pp. 66–92. ISBN 978-0-547-48849-3.
- Yamaguchi, Nobuyuki; Kitchener, Andrew C.; Gilissen, Emmanuel; MacDonald, David W. (2009). "Brain size of the lion (Panthera leo) and the tiger (P. Tigris): Implications for intrageneric phylogeny, intraspecific differences and the effects of captivity". Biological Journal of the Linnean Society 98 (1): 85–93. doi:10.1111/j.1095-8312.2009.01249.x.
- Healy, Susan D.; Rowe, Candy (2007). "A critique of comparative studies of brain size". Proceedings of the Royal Society B: Biological Sciences 274 (1609): 453–64. doi:10.1098/rspb.2006.3748. JSTOR 25223800. PMC 1766390. PMID 17476764.
- Outhwaite, William (2006). The Blackwell dictionary of modern social thought (2nd ed.). Wiley-Blackwell. p. 257. ISBN 1-4051-3456-9.
- Weiner, Irving B.; Craighead, W. Edward (2010). The Corsini Encyclopedia of Psychology 4. John Wiley & Sons. p. 1857.
- Sorabji, Richard (1995). Animal Minds and Human Morals: The Origins of the Western Debate. Cornell University Press. ISBN 0-8014-8298-4.[page needed]
- Allen, Colin (13 October 2010). "Animal Consciousness". In Zalta, Edward N. The Stanford Encyclopedia of Philosophy.
- Nieuwenhuyis, Rudolf; ten Donkelaar, Hendrik Jan; Nicholson, Charles (1998). The Central Nervous System of Vertebrates. ISBN 978-3-540-56013-5.[page needed]
- Chudler, Eric H. "Brain Facts and Figures".[self-published source?]
- Gross, Richard (2010). Psychology: The Science of Mind and Behaviour. ISBN 978-1-4441-0831-6.[page needed]
- Mann, M (1979). "Sets of neurons in somatic cerebral cortex of the cat and their ontogeny". Brain Research Reviews 1 (1): 3–45. doi:10.1016/0165-0173(79)90015-8. PMID 385112.
- "How Smart Is Your Cat?". Cat Watch. Cornell University College of Veterinary Medicine. February 2010.[not in citation given]
- Ananthanarayanan, Rajagopal; Esser, Steven K.; Simon, Horst D.; Modha, Dharmendra S. (2009). "The cat is out of the bag: cortical simulations with 109 neurons, 1013 synapses". Proceedings of the Conference on High Performance Computing Networking, Storage and Analysis - SC '09. pp. 1–12. doi:10.1145/1654059.1654124. ISBN 978-1-60558-744-8.
- Kosslyn, S. M.; Pascual-Leone, A; Felician, O; Camposano, S; Keenan, JP; Thompson, WL; Ganis, G; Sukel, KE; Alpert, NM (1999). "The Role of Area 17 in Visual Imagery: Convergent Evidence from PET and rTMS". Science 284 (5411): 167–70. Bibcode:1999Sci...284..167K. doi:10.1126/science.284.5411.167. PMID 10102821.
- Solnick, Bennett; Davis, Thomas L.; Sterling, Peter (1984). "Numbers of Specific Types of Neuron in Layer IVab of Cat Striate Cortex". Proceedings of the National Academy of Sciences of the United States of America 81 (12): 3898–900. Bibcode:1984PNAS...81.3898S. doi:10.1073/pnas.81.12.3898. PMC 345329. PMID 6587398.
- Beaulieu, Clermont; Colonnier, Marc (1989). "Number of neurons in individual laminae of areas 3B, 4?, and 6a? Of the cat cerebral cortex: A comparison with major visual areas". The Journal of Comparative Neurology 279 (2): 228–34. doi:10.1002/cne.902790206. PMID 2913067.
- "Gyrencephalic Definition". Serendip. Retrieved 6 February 2012.
- Smith, J. M.; James, M. F.; Bockhorst, K. H. J.; Smith, M. I.; Bradley, D. P.; Papadakis, N. G.; Carpenter, T. A.; Parsons, A. A. et al. (2001). "Investigation of feline brain anatomy for the detection of cortical spreading depression with magnetic resonance imaging". Journal of Anatomy 198 (5): 537–54. doi:10.1017/S002187820100766X. PMC 1468243. PMID 11430693.
- Kurths, Jürgen; Zhou, Changsong; Zamora-López, Gorka (2011). "Exploring Brain Function from Anatomical Connectivity". Frontiers in Neuroscience 5: 83. doi:10.3389/fnins.2011.00083. PMC 3124130. PMID 21734863.
- Feig, Sherry; Harting, John K. (1998). "Corticocortical communication via the thalamus: Ultrastructural studies of corticothalamic projections from area 17 to the lateral posterior nucleus of the cat and inferior pulvinar nucleus of the owl monkey". The Journal of Comparative Neurology 395 (3): 281–95. doi:10.1002/(SICI)1096-9861(19980808)395:3<281::AID-CNE2>3.0.CO;2-Z. PMID 9596524.
- Huang, Chuong C; Lindsley, Donald B (1973). "Polysensory responses and sensory interaction in pulvinar and related postero-lateral thalamic nuclei in cat". Electroencephalography and Clinical Neurophysiology 34 (3): 265–80. doi:10.1016/0013-4694(73)90254-X. PMID 4129614.
- Bear, Mark F.; Connors, Barry W.; Paradiso, Michael A. (2007). "Neural Components of Aggression Beyond the Amygdala". Neuroscience: Exploring the Brain. pp. 579–81. ISBN 978-0-7817-6003-4.
- Norris, Kenneth S., ed. (1966). "The Diencephalon". Whales, Dolphins, and Porpoises. pp. 239–47. ISBN 978-0-520-03283-5.
- Fourment, A.; Hirsch, J.C. (1980). "Synaptic potentials in cat's lateral geniculate neurons during natural sleep with special reference to paradoxical sleep". Neuroscience Letters 16 (2): 149–54. doi:10.1016/0304-3940(80)90335-3. PMID 6302571.
- Sherman, S. Murray (2007). "The thalamus is more than just a relay". Current Opinion in Neurobiology 17 (4): 417–22. doi:10.1016/j.conb.2007.07.003. PMC 2753250. PMID 17707635.
- Sherman, S. (2006). "Thalamus". Scholarpedia 1 (9): 1583. doi:10.4249/scholarpedia.1583.
- Melik-Musyan, A. B.; Fanardjyan, V. V. (1998). "Projections of the central cerebellar nuclei to the intralaminar thalamic nuclei in cats". Neurophysiology 30: 39–47. doi:10.1007/BF02463111.
- Grouse, Lawrence D.; Schrier, Bruce K.; Nelson, Phillip G. (1979). "Effect of visual experience on gene expression during the development of stimulus specificity in cat brain". Experimental Neurology 64 (2): 354–64. doi:10.1016/0014-4886(79)90275-9. PMID 428511.
- Okujav, Vazha; Natishvili, Teimuraz; Gogeshvili, Ketevan; Gurashvili, Thea; Chipashvili, Senera; Bagashvili, Tamila; Andronikashvili, George; Okujava, Natela (2009). "Visual Recognition Memory in Cats: Effects of Massed vs. Distributed Trials". Bulletin of the Georgian National Academy of Sciences 3 (2): 168–72.
- Okujava, Vazha; Natishvili, Teimuraz; Mishkin, Mortime; Gurashvili, Thea; Chipashvili, Senera; Bagashvili, Tamil; Andronikashvili, George; Kvernadze, George (2005). "One-trial visual recognition in cats". Acta Neurobiologiae Experimentalis 65 (2): 205–11. PMID 15960308.
- Fiset, Sylvain; Doré, François Y. (1996). "Spatial encoding in domestic cats (Felis catus)". Journal of Experimental Psychology: Animal Behavior Processes 22 (4): 420–37. doi:10.1037/0097-7403.22.4.420. PMID 8865610.
- Adamec, R.E.; Stark-Adamec, C. (1983). "Partial kindling and emotional bias in the cat: Lasting aftereffects of partial kindling of the ventral hippocampus". Behavioral and Neural Biology 38 (2): 205–22. doi:10.1016/S0163-1047(83)90212-1. PMID 6314985.
- Marcos, P; Coveñas, R; Narvaez, J.A; Aguirre, J.A; Tramu, G; Gonzalez–Baron, S (1998). "Neuropeptides in the Cat Amygdala". Brain Research Bulletin 45 (3): 261–8. doi:10.1016/S0361-9230(97)00343-2. PMID 9580215.
- Forrest, David V. (2002). "The Executive Brain: Frontal Lobes and the Civilized Mind". American Journal of Psychiatry 159 (9): 1615–6. doi:10.1176/appi.ajp.159.9.1615.
- Diamond, Adele (2011). "Frontal Lobe Involvement in Cognitive Changes During the First Year of Life". In Gibson, Kathleen R.; Petersen, Anne C. Brain Maturation and Cognitive Development: Comparative and Cross-Cultural Perspectives. pp. 127–80. ISBN 978-1-4128-4450-5.
- Clarke, Stephanie; de Ribaupierre, François; Bajo, Victoria M.; Rouiller, Eric M.; Kraftsik, Rudolf (1995). "The auditory pathway in cat corpus callosum". Experimental Brain Research 104 (3): 534–40. doi:10.1007/BF00231988. PMID 7589305.
- Payne, B. R.; Siwek, D. F. (1991). "The Visual Map in the Corpus Callosum of the Cat". Cerebral Cortex 1 (2): 173–88. doi:10.1093/cercor/1.2.173. PMID 1822731.
- Ebner, Ford F.; Myers, Ronald E. (1965). "Distribution of corpus callosum and anterior commissure in cat and raccoon". The Journal of Comparative Neurology 124 (3): 353–65. doi:10.1002/cne.901240306. PMID 5861718.
- Boya, Jesús; Calvo, Jose Luis; Rancano, Dolores (1995). "Structure of the pineal gland in the adult cat". Journal of Pineal Research 18 (2): 112–8. doi:10.1111/j.1600-079X.1995.tb00148.x. PMID 7629690.
- Peters, D. A. V.; McGeer, P. L.; McGeer, E. G. (1968). "The Distribution of Tryptophan Hydroxylase in Cat Brain". Journal of Neurochemistry 15 (12): 1431–5. doi:10.1111/j.1471-4159.1968.tb05924.x. PMID 5305846.
- ion[Retrieved 2011-12-29][verification needed]
- V. Edgson, I. Marber The food doctor: healing foods for mind and body (160 pages)Collins & Brown, 1999 ISBN 1855856824[not in citation given]
- Datz, Craig (2011). "Cats: Health, Diseases, and Prevention". In Davis, Radford G. Caring for Family Pets: Choosing and Keeping Our Companion Animals Healthy: Choosing and Keeping Our Companion Animals Healthy. pp. 77–95. ISBN 978-0-313-38528-5.
- Reingold, Eyal (3 October 2007). "Human Intelligence". University of Toronto.[self-published source?]
- Gläscher, Jan; Tranel, Daniel; Paul, Lynn K.; Rudrauf, David; Rorden, Chris; Hornaday, Amanda; Grabowski, Thomas; Damasio, Hanna; Adolphs, Ralph (2009). "Lesion Mapping of Cognitive Abilities Linked to Intelligence". Neuron 61 (5): 681–91. doi:10.1016/j.neuron.2009.01.026. PMC 2728583. PMID 19285465. Lay summary – Caltech (11 March 2009).
- Fiset, Sylvain; Doré, François Y. (2006). "Duration of cats' (Felis catus) working memory for disappearing objects". Animal Cognition 9 (1): 62–70. doi:10.1007/s10071-005-0005-4. PMID 16133631.
- Roth & Dicke 2005[verification needed]
- Haug, H (1987). "Brain sizes, surfaces, and neuronal sizes of the cortex cerebri: A stereological investigation of man and his variability and a comparison with some mammals (primates, whales, marsupials, insectivores, and one elephant)". The American journal of anatomy 180 (2): 126–42. doi:10.1002/aja.1001800203. PMID 3673918.
- Doré, François Y. (1990). "Search behaviour of cats (Felis catus) in an invisible displacement test: Cognition and experience". Canadian Journal of Psychology 44 (3): 359–70. doi:10.1037/h0084262. PMID 2224640.
- Dumas, Claude (1992). "Object permanence in cats (Felis catus): An ecological approach to the study of invisible displacements". Journal of Comparative Psychology 106 (4): 404–10. doi:10.1037/0735-7036.106.4.404. PMID 1451424.
- Dumas, Claude; Doré, François Y. (1991). "Cognitive development in kittens (Felis catus): An observational study of object permanence and sensorimotor intelligence". Journal of Comparative Psychology 105 (4): 357–65. doi:10.1037/0735-7036.105.4.357. PMID 1778068.
- Heishman, Miriam; Conant, Mindy; Pasnak, Robert (1995). "Human Analog Tests of the Sixth Stage of Object Permanence". Perceptual and Motor Skills 80 (3c): 1059–68. doi:10.2466/pms.1995.80.3c.1059. PMID 7478858.
- "The Intelligent Cat". Cats International.[unreliable source?]
- Jouvet, M. (2008). "Telencephalic and Rhombencephalic Sleep in the Cat". Ciba Foundation Symposium – the Nature of Sleep. Novartis Foundation Symposia. pp. 188–208. doi:10.1002/9780470719220.ch9. ISBN 978-0-470-71922-0.
- Siegel, Jerome M (2006). "The stuff dreams are made of: Anatomical substrates of REM sleep". Nature Neuroscience 9 (6): 721–2. doi:10.1038/nn0606-721. PMID 16732200.
- Hazra, J. (1970). "Effect of hemicholinium-3 on slow wave and paradoxical sleep of cat". European Journal of Pharmacology 11 (3): 395–7. doi:10.1016/0014-2999(70)90018-X. PMID 5477316.
- Stock, Judith A. Pet Place. 1 January 2011. Web. 24 March 2011.[verification needed]
- Pawprints and Purrs. Cat Health. 11 October 2010. Web. 24 March 2011.[verification needed]
- Memory Loss With Aging. Family Doctor. 22 January 1996. Web. 24 March 2011.
- Boone 1956[verification needed]
- Fox 1980[verification needed]
- Driscoll, C. A.; Menotti-Raymond, M.; Roca, A. L.; Hupe, K.; Johnson, W. E.; Geffen, E.; Harley, E. H.; Delibes, M. et al. (2007). "The Near Eastern Origin of Cat Domestication". Science 317 (5837): 519–23. Bibcode:2007Sci...317..519D. doi:10.1126/science.1139518. PMID 17600185.
- "Evolution of the cat". The Feline Advisory Bureau.
- Driscoll, Carlos A.; MacDonald, David W.; O'Brien, Stephen J. (2009). "Colloquium Papers: From wild animals to domestic pets, an evolutionary view of domestication". Proceedings of the National Academy of Sciences 106 (Suppl 1): 9971–8. Bibcode:2009PNAS..106.9971D. doi:10.1073/pnas.0901586106. JSTOR 40428411. PMC 2702791. PMID 19528637.
- Carlstead, Kathy; Brown, Janine L.; Seidensticker, John (1993). "Behavioral and adrenocortical responses to environmental changes in leopard cats (Felis bengalensis)". Zoo Biology 12 (4): 321–31. doi:10.1002/zoo.1430120403.
- "Rare scavenging wild cat - Jaguar". Stalking the Jaguar. BBCWorldwide. Retrieved 24 December 2011.
- cutoffresonance. "Scavenging cat caught in the act". Retrieved 24 December 2011.[unreliable source?]
- Stanford, Craig B.; Bunn, Henry T., eds. (2001). Meat-Eating and Human Evolution. ISBN 978-0-19-535129-3.[page needed]
- Linseele, Veerle; Van Neer, Wim; Hendrickx, Stan (2007). "Evidence for early cat taming in Egypt". Journal of Archaeological Science 34 (12): 2081–90. doi:10.1016/j.jas.2007.02.019.
- Tobias, Philip V. (1992). "Paleoecology of Hominid Emergence". In Schopf, J. William. Major Events in the History of Life. pp. 147–58. ISBN 978-0-86720-268-7.
- Croitor, Roman (17 March 2010). "On supposed ecological relationship of the early representatives of the genus Homo and saber-toothed cats". SciTopics. Retrieved 26 June 2013.
- Hart, Donna; Sussman, Robert W. (2011). "The Influence of Predation on Primate and Early Human Evolution: Impetus for Cooperation". In Sussman, Robert W.; Cloninger, C. Robert. Origins of Altruism and Cooperation. pp. 19–40. doi:10.1007/978-1-4419-9520-9_3. ISBN 978-1-4419-9519-3.
- web.archive.org [Retrieved 2011-12-26]
- Jordán, Ferenc; Liu, Wei-Chung; Davis, Andrew J. (2006). "Topological keystone species: Measures of positional importance in food webs". Oikos 112 (3): 535–46. doi:10.1111/j.0030-1299.2006.13724.x.
- Seidensticker, John (1987). "Bearing Witness: Observations on the Extinction of Panthera tigris balica and Panthera tigris sondaica". In Tilson, Ronald Lewis; Seal, Ulysses S. Tigers of the world: the biology, biopolitics, management, and conservation of an endangered species. Park Ridge, N.J.: Noyes Data. pp. 1–7. ISBN 978-0-8155-1133-5.
- Thorndike, Edward Lee (1911). Animal Intelligence. Macmillian Company. p. 150.
- D.Bernstein; L. A. Penner; A. Clarke-Stewart; E. J. Roy (October 2007). Psychology. Cengage Learning. p. 205. ISBN 978-0-618-87407-1. Retrieved 24 December 2011.
- Thorndike, Edward Lee (1898). Animal Intelligence.[page needed].
- B. Osthaus Meikle, James (16 June 2009). "Cats outsmarted in psychologist's test". The Guardian.
- Pallaud, B. (1984). "Hypotheses on mechanisms underlying observational learning in animals". Behavioural Processes 9 (4): 381. doi:10.1016/0376-6357(84)90024-X.
- Budiansky, Stephen (1911). If a Lion Could Talk: Animal Intelligence and the Evolution of Consciousness. ISBN 978-0-684-83710-9. Retrieved 16 April 2012.
- Chesler, P. (1969). "Maternal Influence in Learning by Observation in Kittens". Science 166 (390): 901–903. Bibcode:1969Sci...166..901C. doi:10.1126/science.166.3907.901. PMID 5345208.
- Case, Linda P. (2003). The cat: its behavior, nutrition, & health. Wiley-Blackwell. ISBN 0-8138-0331-4.
- Turner, D. C. (2000). The domestic cat: the biology of its behaviour. Cambridge University Press. ISBN 0-521-63648-5.
- Wertheimer, Michael (2012). A Brief History of Psychology. Psychology Press. ISBN 978-1-84872-874-5.
- Boeree, C. George (2 February 2012). "Article on Understanding". Shippensburg University.
- G. Popovich google.co.uk
- [Retrieved 2011-12-27]
- Sumathi, S.; Hamsapriya, T.; Surekha, P. (2008). Evolutionary intelligence: an introduction to theory and applications with Matlab. ISBN 978-3-540-75382-7.[page needed]
- Reiss, Michael J.; Straughan, Roger (2001). Improving Nature?: The Science and Ethics of Genetic Engineering. ISBN 978-0-521-00847-1.[page needed]
- Rollin, Bernard E. (1995). The Frankenstein syndrome: ethical and social issues in the genetic engineering of animals. ISBN 978-0-521-47807-6.[page needed]
- Verhoog, H (2007). "The tension between common sense and scientific perception of animals: Recent developments in research on animal integrity". NJAS – Wageningen Journal of Life Sciences 54 (4): 361–73. doi:10.1016/S1573-5214(07)80009-1.
- Pontius, J. U.; Mullikin, J. C.; Smith, D. R.; Lindblad-Toh, K.; Gnerre, S.; Clamp, M.; Chang, J.; Stephens, R. et al. (2007). "Initial sequence and comparative analysis of the cat genome". Genome Research 17 (11): 1675–89. doi:10.1101/gr.6380007. PMC 2045150. PMID 17975172.
- Gosso, M. F.; Van Belzen, M.; De Geus, E. J. C.; Polderman, J. C.; Heutink, P.; Boomsma, D. I.; Posthuma, D. (2006). "Association between the CHRM2 gene and intelligence in a sample of 304 Dutch families". Genes, Brain and Behavior 5 (8): 577–84. doi:10.1111/j.1601-183X.2006.00211.x. PMID 17081262.
- "IBM computer simulates cat's cerebral cortex". NBC News. Associated Press. 18 November 2009. Retrieved 26 June 2013.
- Fischetti, Mark (25 October 2011). scientificamerican.com "IBM Simulates 4.5 percent of the Human Brain, and All of the Cat Brain". Nature America, Inc. Retrieved 2 February 2012.
- Adee, Sally (18 November 2009). "IBM Unveils a New Brain Simulator". IEEE Spectrum. Retrieved 2 February 2012.
- Adee, Sally (January 2010). "Two simulations and an angry e-mail reveal the conflicting goals of supercomputer brain modeling". IEEE Spectrum. Retrieved 2 February 2012.
- Burt, Jeffrey (24 November 2009). "Rival Scientist Calls IBM Cat Brain Simulation a Scam". eWeek. Retrieved 2 February 2012.
- Grossberg, Stephen; Grunewald, Alexander (2002). "Temporal dynamics of binocular disparity processing with corticogeniculate interactions". Neural Networks 15 (2): 181–200. doi:10.1016/S0893-6080(01)00149-6. PMID 12022507.
- Koch, Christof; Tononi, Giulio (June 2008). "Can Machines Be Conscious?". IEEE Spectrum. Retrieved 31 December 2009.
- Bergler, Reinhold "Man and Cat: The Benefits of Cat Ownership" Blackwell Scientific Publications (1989)
- Bradshaw, John W S "The Behaviour of the Domestic Cat" C A B International (1992)
- Chesler, P. (1969). "Maternal Influence in Learning by Observation in Kittens". Science 166 (3907): 901–3. Bibcode:1969Sci...166..901C. doi:10.1126/science.166.3907.901. PMID 5345208.
- Hobhouse, L T "Mind in Evolution" MacMillan, London (1915)
- Turner, Dennis C, and Patrick Bateson. "The Domestic Cat: The Biology of Its Behaviour" Cambridge University Press (1988)
- Miles, R. C. (1958). "Learning in kittens with manipulatory, exploratory, and food incentives". Journal of Comparative and Physiological Psychology 51 (1): 39–42. doi:10.1037/h0049255. PMID 13513843.
- Neville, Peter "Claws and Purrs" Sidgwick & Jackson (1992)
- Neville, Peter "Do Cats Need Shrinks" Sidgwick & Jackson (1990)
- Voith, VL (1981). "You, too, can teach a cat tricks (examples of shaping, second-order reinforcement, and constraints on learning)". Modern veterinary practice 62 (8): 639–42. PMID 7290076.
- D.M.Fankhauser biology.clc.uc.edu Removal and study of the cat brain and Cranial nerves of the cat biology.clc.uc.edu [Retrieved 2011-12-22] (images and instruction) for an anatomy and physiology class for the dissecting of the brain of a cat