Global precedence

Global precedence is the finding that, when presented with a stimulus containing both a global and local feature, an individual more readily identifies the global feature. The global aspect of an object the larger overall image of a whole, while the local aspect is the individual features that make up this larger whole. This action is referred to as global processing. Though global processing has largely been regarded as preferential over local processing, local preference also occurs in certain circumstances and individuals. Global precedence is closely related to the Gestalt principles of grouping in that the global whole is a grouping of proximal and similar objects. Within global precedence there is also the global interference effect. This is the effect that when directed to identify the local characteristic, the global characteristic interferes by slowing the reaction time.

Basic methods

The basic stimuli utilized in experiments regarding global precedence is the use of Navon figures. A Navon figure consists of a large letter composed of many small letters that either match the large letter or do not. Variations of the original Navon figure have been made to include both shapes and objects. A Navon figure is presented to participants and they must identify the object. Participants are told before the presentation whether to focus on the global or local level. Experimenters measure both the accuracy and response time of the responses.

Navon figures are commonly used in priming to determine the effects of direction towards global or local processing on other tasks.

Consistent, neutral, and conflicting Navon figures

Specific results and theories

Cultural and race differences

When Navon figure stimuli similar to that originally presented by Navon is presented to participants from a remote African culture, the Himba, results vary from Navon’s original findings. A local precedence is observed. Conversely, this local precedence did not apply to facial recognition, in which the Himba have equal global processing and worse local processing of inverted faces than western participants.

This difference in precedence for Navon figure stimuli can be attributed to cultural differences in occupations or the practice of reading and writing. Local precedence is often found in individuals with disorders, so it is sometimes connected to disorder; however, the study of the Himba indicates otherwise. The Himba are a normally functioning society capable of global and local processing, but still show local precedence. Also, the general importance of facial recognition is demonstrated by the equally strong abilities to globally process faces.

Varying stimuli

Stimuli are either meaningful or meaningless. For example, letters and familiar objects, like a cup, are meaningful, while an unidentifiable and non-geometric shapes are not. With both types of stimuli, the global advantage is observed, but the global interference effect only occurs with meaningful stimuli. In other words, when the global object is meaningful, the reaction time for identification of the local feature increases.

This indicates that within global precedence, global advantage and global interference rely on two separate mechanisms.Global-local interference occurs as a result of automatic processing of objects. The theory is that the global precedence effect has is a sensory mechanism active in global advantage, whereas automatic and semantic processes are active in the interference effect.

Affect

With positive priming, participants respond faster to local targets. The participants are capable of both global and local precedence. This indicates that mood does not dictate ones processing abilities are not affected by mood, but rather ones preferences. Negative priming was also shown to reduce flexibility. The prime material was self-generated and therefore not very controlled.

The result that negative priming reduces flexibility is correlates to the Psi theory which states that negative emotion inhibits one’s access to extension memory so that cognitive flexibility is also reduced. Also, this supports the theory that positive affect increases cognitive flexibility.

The proposition of increased cognitive flexibility has been expanded upon. When emotional priming words without individualistic specificity are used as the stimuli. The finding that positive mood priming increases cognitive flexibility still holds true in this condition. Also, they used visual emotion of priming with pictures instead of words and the results were still maintained of increased cognitive flexibility with positive affect priming. Instead of simply testing to see if local processing was promoted with positive affect, it was found that the positive priming improves one’s abilities in their own non-preferred dimension. For example, one preferring the local aspect of stimuli would show increased performance in identifying the global aspect and vice versa.

This supports the flexibility theory that positive affect does not simply improve performance in local processing, but rather improves cognitive flexibility.

Facial perception

Faces are largely regarded as being processed in a special way and holistically, or in a global sense. Navon stimuli can have either global precedence or local precedence depending on the spacing and size of the stimuli. Priming aides the recognition of faces when the response elicited matched the precedence of the figure. For example, if the stimuli has local precedence and the participant is cued to respond with the local feature identification, their accuracy in facial recognition is aided by the correlation between the stimuli and response. The same occurs when global responses are asked of global stimuli.

When given a facial task that requires local processing for identification, the results of the Navon priming differed. It aided participants’ facial recognition when they were forced to show cognitive flexibility in their priming responses by responding to global precedence stimuli with local responses and vice versa.

One theory to explain these results is that by responding to the non-prevalent aspect of the stimuli, one must switch from automatic response to controlled response. Identifying faces is automatic, so it is aided by the automatic processing of corresponding stimuli and responses. A task that requires controlled response is aided by identifying the non-dominant feature of a Navon stimuli, which requires controlled processing. This indicates that face recognition is dependent on type of attention rather than locus of focus on holistic features or global features.

Individuals demonstrating a stronger global precedence show differing facial recognition than those demonstrating weak global precedence in the face inversion effect. Both groups show better identification of upright faces than inverted faces. When identifying inverted faces, those showing greater global precedence also show a more prominent effect of facial inversion. Those showing a stronger global precedence also have a greater deficit in identification abilities when the faces are inverted.

This correlates to the idea that upright faces are processed holistically, or with a special mechanism. Those with stronger global precedence should perform better at holistically processing a face. Stronger global precedence should show a greater decrease in accuracy of identification of inverted faces because the task relies on local processing. Also, the propensity for globality varies among individuals, supporting the idea that individual differences in processing styles contribute to facial recognition.

Disorders

Children with autism have shown a much weaker global precedence than those without the disorder. They are not more attentive to local detail, but rather they were simply less sensitive to global features. Autistic children are found to be worse at identifying emotion in both humans and canines, and their ability to identify canine age. There are correlations between global or local performance on a task and the ability to identify emotion and canine age. In both cases, global responses correlated to a better identification, while unrelated responses on the global-local identification task correlated with a negative affect on the accuracy of emotion and canine age identification. Within autistic children, those who respond more globally to a discrimination task perform better on emotion and canine age tasks. For autistic children, the ability to identify emotions and age in autistic children corresponds to their pension for global processing. Autistic children’s social struggles can be attributed to these inabilities, caused by a lack of global precedence.

One explanation is a possible biological dysfunction in the brain region where facial processing occurs. Research indicates that global processing, facial recognition and emotional expression recognition are all linked to the right hemisphere.

Interindividual characteristics

The degree of global precedence has been found differ in relation to the individual variable of field dependency. Field dependency is the amount that one relies on Gestalt laws of perceptual organization. High field dependency corresponds to a greater bias toward the global level, while field independence corresponds to a lesser dependency on the global level.

This indicates that interindividual characteristics have an effect on the prevalence of global precedence and can possibly explain variable findings of global precedence in other studies. Global and local processing exist on a continuum, where one specific description of precedence does not suffice to describe the interindividual differences.

References

Linnea Ng (talk) 03:46, 19 October 2011 (UTC)