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 embodies the larger, overall image as a whole, whereas the local aspect consists of the individual features that make up this larger whole. Global processing is the act of processing a visual stimulus holistically. Although global processing is generally more prevalent than local processing, local preference also occurs under certain circumstances and for certain 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. The global interference effect is when individuals are directed to identify the local characteristic, the global characteristic interferes by slowing the reaction time.

Basic methods

The Navon figures is the basic stimulus utilized in experiments regarding global precedence. A Navon figure consists of a large letter composed of many small letters that either match or do not match the large letter. Variations of the original Navon figure have been made to include both shapes and objects. When a Navon figure is presented to participants, they will be given one of two task. Firstly,they may either be asked to identify the global or the local component. Participants are told before the presentation of the stimulus whether to focus on a global or local level. Experimenters measure both the accuracy and reaction time of responses.Secondly, the participants may be presented with a target stimulus, and then two other visuals. One of the visuals matches the target stimulus on the global level, while the other visual matches the target stimulus on the local level. In this condition, experimenters note which of the two visuals, the global or local, is chosen to match the target stimulus.

Consistent, neutral, and conflicting Navon figures

Specific results and theories

Cultural and racial 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 does not apply to facial recognition, in which the Himba have equal global processing as 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 described as a consequence of 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.

Varying stimuli

Stimuli are either meaningful or meaningless. For example, letters and familiar objects, like a cup, are meaningful, while unidentifiable and non-geometric shapes are not. In 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 supports the theory 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 global objects. The theory is that the global precedence effect has a sensory mechanism active in global advantage, whereas automatic and semantic processes are active in the interference effect.

Affect

With positive priming, participants' local response times decrease and the effect of global precedence is lessened. Oppositely, negative priming shown to slow local responses. Individuals are capable of both global and local processing; mood does not dictate one's processing abilities, but rather one's preferences. In the study that found these results, the priming stimuli was self-generated.

The result that negative priming reduces flexibility 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. Also visual primes instead of words result in increased cognitive flexibility with positive affect priming. Instead of simply testing to see if local processing is promoted with positive affect, it is found that positive priming improves one’s abilities in his 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 further supports the flexibility theory that positive affect does not simply improve performance in local processing, but rather improves overall cognitive flexibility.

Faces

Faces are largely regarded as being processed by a special mechanism 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. A local precedence Navon figure is predisposed to local processing, and the converse is true for a global precedence Navon figure. Priming aides the recognition of faces when the response elicited matches 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, his 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 differ. It aides participants’ facial recognition when they are forced to show cognitive flexibility in their priming responses by responding to global precedence stimuli with local responses and vice versa.

One theory that explains 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 facial recognition depends 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 weaker global precedence in regards to the face inversion effect. Both groups show better identification of upright faces than inverted faces. When identifying inverted faces, those showing stronger global precedence 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; their identification abilities decrease more from upright identification to inverted identification than weak global precedence individuals.

This correlates to the theory that upright faces are processed holistically, or with a special mechanism. Those with stronger global precedence should perform better at holistically processing a face upright. 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

The Navon figure has been used in relating theories regarding processing to assessing cognitive learning disabilities, such as developmental dyslexia, dyscalculia, obsessive-compulsive personality disorder, and autism.

When given a Navon figure test, people with dyslexia have difficulty automatically identifying graphemes with phonemes, but they do not have problems identifying numbers with magnitudes. On the other hand, people with dyscalculia have difficulty automatically identifying numbers with magnitudes, but not with letters and phonemes. This suggests a dissociation between subjects with dyslexia and dyscalculia; these developmental learning disabilities do not cause general problems with identifying symbols to their mental representations, but rather crate specific challenges.

Individuals with obsessive-compulsive personality disorder characteristically have sharp, detail-oriented attentions, tending to focus more intensely on specifics rather than the larger context. In terms of visual perception, it has been found that OCPD subjects are prone to be distracted by the local aspects of the stimuli when asked to identify global aspects of figures, such as the Navon figure. This supports the detail-oriented attentional style of OCPD.

Children with autism have demonstrated much weaker global precedence than those without the disorder. They are not more attentive to local detail, but rather they are 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 than children without the disorder. 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 correlate to a better identification. Within the group of 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 corresponds to their pension for global processing.Autistic children’s social struggles can be connected 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. A defect in that area would explain the characteristics of autism.

Interindividual characteristics

The degree of global precedence one demonstrates has been found to differ in relation to the variable of an individual's 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 all the interindividual differences.