A cardiac measure of cerebral asymmetries in infant auditory perception.

Examined the utility of cardiac habituation response recovery as a method for assessing infant cerebral asymmetries in auditory perception in a dichotic listening test. In a within-Ss design 12 3-mo-old infants were given a series of 4 10-trial tests during which their cardiac responses were habituated to a pair of dichotic speech syllables or music notes. The 10th trial in each test was a test trial on which one ear received its habituation stimulus while the other ear received a novel stimulus of the same type as the habituation pair (speech or music). Both stimulus type and ear receiving the novel stimulus were counterbalanced across tests. Overall, Ss' cardiac responses habituated during the tests and showed differential recovery to the novel stimuli. Specifically, greater response recovery occurred when a novel speech syllable was presented to the right, than to the left ear. Conversely, greater response recovery was found when a novel music note was presented to the left than to the right ear. Results indicate that young infants show a pattern of auditory perceptual asymmetries much like that found in older children and adults. Findings are consistent with the theory that in man the left hemisphere is superior at processing speech and the right hemisphere superior with nonspeech. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental sex differences in global-local perceptual bias.

Previous developmental studies have indicated that boys tend to perform better than girls on tasks associated with the right hemisphere (e.g., spatial tasks), whereas girls perform better on tasks associated with the left hemisphere (e.g., verbal tasks). Extending this body of literature to what is known about hemispheric specialization of visuospatial processing, we predicted that boys would be more global than girls in their perception of visual hierarchical stimuli. Forty girls and 39 boys between the ages of 4 and 12 years were administered a perceptual judgment task previously used by Kimchi and Palmer (see record 1983-02534-001). Boys were significantly more global in their perceptual judgments than girls at all ages. Younger children of both sexes were less global than older children. Results were consistent with developmental models that suggest an early left-hemisphere advantage for girls and a right-hemisphere advantage for boys. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemispheric aymmetries in adults' perception of infant emotional expressions.

Accounts of emotion lateralization propose either overall right hemisphere (RH) advantage or differential RH vs left hemisphere (LH) involvement depending on the negative–positive valence of emotions. Perceptual studies generally show RH specialization. Yet viewer emotional responses may enhance valence effects. Because infant faces elicit heightened emotion in viewers, perceptual asymmetries with chimeric infant faces were assessed. First, it was determined that chimeras must be paired with their counterparts, not their mirror images, to tap viewers' sensitivity to adult facial asymmetries. Results showed an RH perceptual bias for infant cries but bihemispheric sensitivity to asymmetries in infant smiles. This effect was not due to LH featural vs RH holistic processing and held for additional, intensity-matched, spontaneous expressions. Specialized RH sensitivity to infant cries may reflect an evolutionary advantage for rapid response to infant distress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural mechanisms of global and local processing. A combined PET and ERP study

The neural mechanisms of hierarchical stimulus processing were investigated using a combined event-related potentials (ERPs) and positron emission tomography (PET) approach. Healthy subjects were tested under two conditions that involved selective or divided attention between local and global levels of hierarchical letter stimuli in order to determine whether and where hemispheric differences might exist in the processing of local versus global information. When attention was divided between global and local levels, the N2 component of the ERPs (260- to 360-msec latency) elicited by the target stimuli showed asymmetries in amplitude over the two hemispheres. The N2 to local targets was larger over the left hemisphere, but the N2 to global targets tended to be slightly larger over the right hemisphere. However, the shorter-latency, sensory-evoked P1 component (90- to 150-msec latency) was not different for global versus local targets under conditions of divided attention. In contrast, during selective attention to either global or local targets, asymmetries in the N2 component were not observed. But under selective attention conditions, the sensory-evoked P1 components in the extrastriate cortex were enlarged for global versus local attention. Increased regional cerebral blood flow in the posterior fusiform gyrus bilaterally was observed in the PET data during selective attention to either global or local targets, but neither these nor the P1 component showed any tendency toward hemispheric difference for global versus local attention. Neither were there any activations observed in the parietal lobe during selective attention to global versus local targets. Together these data indicate that early sensory inputs are not modulated to gate global versus local information differentially into the two hemispheres. Rather, later stages of processing that may be asymmetrically organized in the left and right hemispheres operate in parallel to process global and local aspects of complex stimuli (i.e., the N2 effect of the ERPs). This pattern of results supports models proposing that spatial frequency analysis is only asymmetric at higher stages of perceptual processing and not at the earliest stages of visual cortical analysis.     

Neurocognitive underpinnings of face perception: Further evidence of distinct person and group perception processes.

A model of social perception is presented and tested. The model is based on cognitive neuroscience models and proposes that the right cerebral hemisphere is more efficient at processing combinations of features whereas the left hemisphere is superior at identifying single features. These processes are hypothesized to produce person and group-based representations, respectively. Individuating or personalizing experience with an outgroup member was expected to facilitate the perception of the individuating features and inhibit the perception of the group features. In the presented study, participants were asked to learn about various ingroup and outgroup targets. Later, participants demonstrated that categorization response speeds to old targets were slower in the left hemisphere than in the right, particularly for outgroup members, as predicted. These findings are discussed for their relevance to models of social perception and stereotyping. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention to hierarchical level influences attentional selection of spatial scale.

Ample evidence suggests that global perception may involve low spatial frequency (LSF) processing and that local perception may involve high spatial frequency (HSF) processing (Shulman, Sullivan, Gish, & Sakoda, 1986; Shulman & Wilson, 1987; Robertson, 1996). It is debated whether SF selection is a low-level mechanism associating global and local information with absolute LSF and HSF content, or whether it is a higher level mechanism involving a selective process that defines the SF range in which global and local can then be relatively defined. The present study provides support for the latter claim by demonstrating that allocating attention to global or local levels of hierarchical displays biased selection of LSFs or HSFs, respectively, in subsequently presented compound gratings. This bias occurred despite a change in the response dimension (from letter identification in the hierarchical stimulus to orientation discrimination in the grating) and despite a difference in retinal location of the hierarchical stimuli and the grating stimulus. Moreover, the bias was determined by the relationship between the 2 SFs in the compound grating (i.e., their relative frequency) rather than the absolute SF values. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Global and local processing in adult humans (Homo sapiens), 5-year-old children (Homo sapiens), and adult cotton-top tamarins (Saguinus oedipus).

This study compared adults (Homo sapiens), young children (Homo sapiens), and adult tamarins (Saguinus oedipus) while they discriminated global and local properties of stimuli. Subjects were trained to discriminate a circle made of circle elements from a square made of square elements and were tested with circles made of squares and squares made of circles. Adult humans showed a global bias in testing that was unaffected by the density of the elements in the stimuli. Children showed a global bias with dense displays but discriminated by both local and global properties with sparse displays. Adult tamarins' biases matched those of the children. The striking similarity between the perceptual processing of adult monkeys and humans diagnosed with autism and the difference between this and normatively developing human perception is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention allocation modulates the processing of hierarchical visual patterns: A comparative analysis of capuchin monkeys (Cebus apella) and humans.

Humans show a global advantage when processing hierarchical visual patterns, and they detect the global level of stimulus structure more accurately and faster than the local level in several stimulus contexts. By contrast, capuchins (Cebus apella) and other monkey species show a strong local advantage. A key factor which, if manipulated, could cause an inversion of this effect in monkeys is still to be found. In this study, we examined whether it was possible to induce attention allocation to global and local levels of perceptual analysis in capuchin monkeys and if by doing so, their local dominance could be reversed. We manipulated attentional bias using a matching-to-sample (MTS) task where the proportion of trials requiring global and local processing varied between conditions. The monkeys were compared with humans tested with the same paradigm. Monkeys showed a local advantage in the local bias condition but a global advantage in the global bias condition. The role of attention in processing was confined to the local trials in a first phase of testing but extended to both local and global trials in the course of task practice. Humans exhibited an overall global dominance and an effect of attentional bias on the speed of processing of the global and local level of the stimuli. These results indicate a role for attention in the processing of hierarchical stimuli in monkeys and are discussed in relation to the extent to which they can explain the differences between capuchin monkeys and humans observed in this and other studies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Anxiety and perceptual structure: Individual differences in neuropsychological function.

Studied the cognitive performance of 24 high and 36 low trait anxious undergraduates under conditions of high and low situational stress, using tasks requiring greater contribution of the right or left hemisphere. In addition, a perceptual task was adapted from visual information processing research to assess Ss' global or analytic approaches to perception; if anxiety increased the left hemisphere's contribution to perception, anxious Ss might be expected to be more analytic and detail oriented. Results show no significant differences on left hemisphere tasks but a significant interaction of trait by state anxiety for right hemisphere tasks: Low trait Ss performed better and high trait Ss performed more poorly under situational stress. Trait anxiety showed a significant main effect on visual information processing strategy, low Ss tending to be more global and high Ss tending to process the stimulus analytically. Results support the utility of a neuropsychological model in describing the effects of emotion on perception. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemispheric and attentional contributions to perceptual organization deficits on the global-local task in schizophrenia.

Right and left hemisphere hypotheses have been proposed to account for cognitive deficits in schizophrenia. To examine these hypotheses, perception of global-local patterns was studied in 22 patients with schizophrenia and 28 normal comparison participants. The patients with schizophrenia showed an abnormally exaggerated global processing advantage when attention was divided between global and local levels but not when participants were instructed to attend to either the local or global level. This finding suggested a local processing (left hemisphere) deficit, which was overcome through strategic attentional allocation (instructional set). When the stimulus visual angle was reduced from 9° to 3°, the normal participants showed a shift from a local to a global processing advantage, but the patients did not. This finding suggested a more subtle deficit in strategic attentional processes that develop through exposure to stimulus context. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Load Theory of Selective Attention and Cognitive Control.

A load theory of attention in which distractor rejection depends on the level and type of load involved in current processing was tested. A series of experiments demonstrates that whereas high perceptual load reduces distractor interference, working memory load or dual-task coordination load increases distractor interference. These findings suggest 2 selective attention mechanisms: a perceptual selection mechanism serving to reduce distractor perception in situations of high perceptual load that exhaust perceptual capacity in processing relevant stimuli and a cognitive control mechanism that reduces interference from perceived distractors as long as cognitive control functions are available to maintain current priorities (low cognitive load). This theory resolves the long-standing early versus late selection debate and clarifies the role of cognitive control in selective attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encouraging the perceptual underdog: Positive affective priming of nonpreferred local–global processes.

Two experiments examined affective priming of global and local perception. Participants attempted to detect a target that might be present as either a global or a local shape. Verbal primes were used in 1 experiment, and pictorial primes were used in the other. In both experiments, positive primes led to improved performance on the nonpreferred dimension. For participants exhibiting global precedence, detection of local targets was significantly improved, whereas for participants exhibiting local precedence, detection of global targets was significantly improved. The results provide support for an interpretation of the effects of positive affective priming in terms of increased perceptual flexibility. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of a lateralized parietal-basal ganglia circuit in hierarchical pattern perception: Evidence from Parkinson's disease.

The role of corticostriatal circuits in hierarchical pattern perception was examined in Parkinson's disease. The hypothesis was tested that patients with right-side onset of motor symptoms (RPD, left hemisphere dysfunction) would be impaired at local level processing because the left posterior temporoparietal junction (TP) emphasizes processing of local information. By contrast, left-side onset patients (LPD; right hemisphere dysfunction) would show impaired global processing because right TP emphasizes global processing. Participants identified targets at local or global levels without and with attention biased toward those levels. Despite normal attentional control between levels, LPD patients showed a single dissociation, demonstrating abnormal global level processing under all conditions, whereas RPD patients showed abnormal local level processing mainly when attention was biased toward the local level. These findings link side of motor symptom onset to visuospatial cognitive abilities that depend upon the contralateral TP, highlighting that side of onset can predict visuospatial impairments, and provide evidence that an inferior parietal-basal ganglia pathway involving the caudate head and the hemispherically asymmetrical TP region is necessary for hierarchical pattern perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cue summation enables perceptual grouping.

In order to study how basic features interact in shape perception, subjects detected target figure presence and identified target figure shape in a combined 2-alternative forced-choice task. Target figures were embedded in Gabor random fields and were defined by feature contrast in spatial frequency, orientation, or both. Two figure classes were used: block figures, which could not be identified at low feature-contrast levels, and lozenge figures, which could be identified to a moderate degree. Results showed a substantial double-cue benefit for both figure classes in detection. In identification, however, a double-cue benefit was practically absent for blocks, whereas, for lozenges, cue summation proved to be much stronger than in detection. The finding that the way basic features interact is modulated by figure class and psychophysical task indicates involvement of 2 distinct perceptual mechanisms in shape perception. The 1st one highlights salient features and enables local grouping on an early feature-specific processing level. The 2nd one is higher level, serves form completion and grouping of salient contours into global shapes, and enables figure perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lateralized perceptual organization deficits on the global-local task in schizotypal personality disorder.

Right and left hemisphere contributions to perceptual organization functions were examined using a divided-attention version of the global-local task in a sample of 21 unmedicated participants diagnosed with schizotypal personality disorder (SPD) and 20 controls. The SPD participants showed an abnormal global processing advantage. When the visual angle of the hierarchical stimuli was increased from 3° to 9°, the controls showed an increasing local processing advantage, but the SPD participants continued to show an abnormal global processing advantage. These findings suggest a local processing deficit on divided-attention versions of the global-local task in schizophrenia spectrum disorders. Female SPD participants, who had less severe interpersonal deficit symptoms, showed a more abnormal global processing advantage. Hemispheric and processing resource mechanisms that might explain these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Primacy of wholistic processing and global/local paradigm: A critical review.

The question of whether perception is analytic or wholistic is an enduring issue in psychology. The global-precedence hypothesis, considered by many as a modern version of the Gestaltist claim about the perceptual primacy of wholes, has generated a large body of research, but the debate still remains very active. This article reviews the research within the global/local paradigm and critically analyzes the assumptions underlyling this paradigm. The extent to which this line of research contributes to understanding the role of wholistic processing on object perception is discussed. It is concluded that one should be very cautious in making inferences about wholistic processing from the processing advantage of the global level of stimulus structure. A distinction is proposed between global properties, defined by their position in the hierarchical structure of the stimulus, and wholistic properties, defined as a function of interrelations among component parts. It is suggested that a direct comparison between processing of wholistic and component properties is needed to support the hypothesis about the perceptual primacy of wholistic processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relations between perceptual and conceptual scope: How global versus local processing fits a focus on similarity versus dissimilarity.

Nine studies showed a bidirectional link (a) between a global processing style and generation of similarities and (b) between a local processing style and generation of dissimilarities. In Experiments 1-4, participants were primed with global versus local perception styles and then asked to work on an allegedly unrelated generation task. Across materials, participants generated more similarities than dissimilarities after global priming, whereas for participants with local priming, the opposite was true. Experiments 5-6 demonstrated a bidirectional link whereby participants who were first instructed to search for similarities attended more to the gestalt of a stimulus than to its details, whereas the reverse was true for those who were initially instructed to search for dissimilarities. Because important psychological variables are correlated with processing styles, in Experiments 7-9, temporal distance, a promotion focus, and high power were predicted and shown to enhance the search for similarities, whereas temporal proximity, a prevention focus, and low power enhanced the search for dissimilarities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pitch perception in chinchillas (Chinchilla laniger): Stimulus generalization using rippled noise.

Rippled noises evoke the perception of pitch in human listeners. Infinitely iterated rippled noise (IIRN) is generated when wideband noise (WBN) is delayed, attenuated, and added to the original WBN through either a positive (+) or a negative (-) feedback loop. The pitch of IIRN[+] is matched to the reciprocal of the delay, whereas the pitch of IIRN[-] for the same delay is an octave lower. Chinchillas (Chinchilla laniger) were trained to discriminate IIRN[+] with a 4-ms delay from IIRN[+] with a 2-ms delay and then tested in a stimulus generalization paradigm with IIRN[+] at delays between 2 and 4 ms. Systematic gradients in behavioral response occurred along the dimension of delay, suggesting that a perceptual dimension corresponding to pitch exists for IIRN[+]. Behavioral responses to IIRN[-] test stimuli were more variable among chinchillas, suggesting that IIRN[-] did not evoke similar pitches relative to IIRN[+]. Systematic gradients in behavioral response were observed when IIRN[-] test stimuli were presented in the context of other IIRN[-] stimuli. Thus, other perceptual cues such as timbre may dominate the pitch cues when IIRN[-] test stimuli are presented in the context of IIRN[+] stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Local and global cross-modal influences between vision and hearing, tasting, smelling, or touching.

It is suggested that the distinction between global versus local processing styles exists across sensory modalities. Activation of one-way of processing in one modality should affect processing styles in a different modality. In 12 studies, auditory, haptic, gustatory or olfactory global versus local processing was induced, and participants were tested with a measure of their global versus local visual attention; the content of this measure was unrelated to the inductions. In a different set of 4 studies, the effect of local versus global visual processing on the way people listen to a poem or touch, taste, and smell objects was examined. In all experiments, global/local processing in 1 modality shifted to global/local processing in the other modality. A final study found more pronounced shifts when compatible processing styles were induced in 2 rather than 1 modality. Moreover, the study explored mediation by relative right versus left hemisphere activation as measured with the line bisection task and accessibility of semantic associations. It is concluded that the effects reflect procedural rather than semantic priming effects that occurred out of participants' awareness. Because global/local processing has been shown to affect higher order processing, future research may activate processing styles in other sensory modalities to produce similar effects. Furthermore, because global/local processing is triggered by a variety of real world variables, one may explore effects on other sensory modalities than vision. The results are consistent with the global versus local processing model, a systems account (GLOMOsys; F?rster & Dannenberg, 2010). (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Interhemispheric relations in processing hierarchical patterns: Evidence from normal and commissurotomized subjects.

On the basis of a review of neuropsychological evidence for several component processes of responding to global and local levels of hierarchically structured patterns, L. C. Robertson and M. R. Lamb (see record 1991-24938-001) hypothesized that interhemispheric communication between posterior cortexes would disrupt the typically interfering effects of global patterns on local response. These studies confirmed this hypothesis in 3 commissurotomized Ss. The normal interaction between visual field presentation and global or local level was present in normal Ss and all 3 patients, but global interference was absent or even reversed in patients. These data are discussed as they relate to the function of the corpus callosum and functional hemisphere asymmetries in responding to global and local levels of hierarchical forms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)