Structural information processing in peripheral vision

Structural visual information processing was investigated in peripheral vision. Perceptual completion, as observed at the blind spot, occurred across a vertical blank stripe in a test pattern, presented in the peripheral visual field. That is, a shape, organized by structural processing, was perceived under critical visual conditions when it was presented in peripheral vision. The results indicate that structural processing, as indicated by perceptual completion, occurs in the peripheral visual information handling process. The results suggest that structural processing of shape information is built into the peripheral visual system and reduces the information load on the higher visual processes under conditions in which visual information is not adequate.     

About face: left-hemisphere involvement in processing physiognomies

Three experiments were concluded to investigate the involvement of the two cerebral hemispheres in processing faces. Perceptual discrimination of pairs of faces was equally speedy overall when the stimuli were presented in the right visual field (RVF) or left visual field (LVF). For faces differing in one or two features, however, a qualitatively different pattern of results was obtained for the two visual fields, and an RVF advantage emerged when the difference lay in the upper part of the faces (Experiment 1). An examination of the discriminability of the facial features from which the faces were constructed (Experiment 2) showed that the processes involved in RVF comparisons of faces were not dependent on the saliency of the features but, rather, followed a top-to-bottom serial analysis of the stimuli; the speed of the processing involved in LVF presentations was a function of the degree of similarity of the different comparison faces. Evidence for a serial type of comparison faces were used (Experiment 3). It was concluded that even though comparisons were equally speedy overall in LVF and RVF presentations, qualitatively different processes take place in the two hemispheres, which prove competent at processing faces, each in its own way. Some methodological problems inherent in tachistoscopic studies are discussed, and it is proposed that the quality of the stimulus representation achieved or required for cognitive processing may be determinant in the emergence of functional hemispheric asymmetries.     

Unconscious processing of color and form in metacontrast masking

Three experiments employed a metacontrast masking procedure to examine the extent and nature of priming effects from visual stimuli not consciously perceived. The results showed effects of unconscious stimuli on subsequent target responses that (1) were more consistent, reliable, and not subject to strategic control, as compared with consciously perceived stimuli (Experiment 1); (2) produced both facilitation and interference of subsequent processing (Experiment 2); and (3) did not influence indirect response-related levels of processing (Experiment 3). These results demonstrate that color and form attributes of unconscious stimuli are sufficiently registered within the visual system to influence behavior, and that some of these unconscious effects occur at early levels of stimulus encoding, prior to higher level perceptual and response-related processes.     

Focal and nonfocal processing of color and form

Langley Porter Neuropychtatrte Institute, University of California, San Francisco. Californta 94122 Response latencies to color are usually shorter than those to form. but sometimes this difference is absent or reversed. Three experiments investigated whether these differences result from differential susceptibility of color and form to extra focal processing. Experiment I showed shorter same-difference latencies to color than to form when two stimuli were presented simultaneously. This difference disappeared or reversed when the two stimuh appeared sequentially. Experiment II. using a multistimulus matching task, found that differences between response latencies to form and color were minimal at the center of the display and increased peripherally. Experiment III showed that eye movements were more frequent in matching forms than colors. Tasks that produced many eye movements had long average latencies, but the relationship between eye movements and latency was not a simple one. There was evidence both for parallel and serial strategies tn the use of the eyes to gather information. The results of these experiments are considered in relation to a theory of distributed attention.     

Interactions between color and word processing in a flanker task

To examine interactions between color and word attributes, participants responded, either manually or vocally, to a central target (color patch or word) flanked by a Stroop stimulus. Color and word attributes of the flanker affected both vocal and manual responding to color patches. Color and word flankers also affected manual responding to word targets, but only word flanker affected vocal responding to word targets. These results are not consistent with models (e.g., translational models) of Stroop tasks, which posit that interactions between colors and words occur only when vocal responding is required.     

Cortical involvement in the semantic processing of coarticulated speech cues

Auditory evoked responses (AER) were recorded from scalp locations over the left and right temporal regions in response to CVC words and nonsense syllables. Various components of the AER were found to vary systematically with changes in stimulus meaning. One such component reflected subcortical involvement in semantic processing. Other components reflected changes in voicing and place of articulation as well as hemisphere differences.     

Attentional processing of location and color cues during driving

Studies have shown that prior information concerning the spatial location of a subsequent target facilitates the selection of that target for further visual processing in three-dimensional (3-D) space. Using Posner's cuing paradigm, our work examined the reaction time of drivers when cue duration and peripheral environment luminance was changed, and explored the effect color and location on reaction time. Experiment 1 showed that reaction time was not affected by cue duration, and that shifts of attention operated more efficiently for cue location validity. Experiment 2 showed that there was no main effect of background luminance on reaction time. Experiment 3 showed that location produces a greater effect than color.     

Attentional processing and the independence of color and orientation

Judgments of the color and shape of a stimulus specified by a cue indicating its location demonstrate stochastic independence. Evidence for the independence of color and orientation was obtained when the cue followed stimulus offset immediately, the cue followed stimulus offset by 2 s, and when either a central or peripheral precue focused attention on the cued stimulus at the time of its presentation. It appears that an object's color and orientation are represented independently even following the attentional focusing thought to support feature integration.     

The involvement of bottom-up saliency processing in endogenous inhibition of return

Participants are faster at detecting a visual target when it appears at a cued, as compared with an uncued, location. In general, a reversal of this cost-benefit pattern is observed after exogenous cuing when the cue-target interval exceeds approximately 250?ms (inhibition of return [IOR]), and not after endogenous cuing. We suggest that, usually, no IOR is found with endogenous cues because no bottom-up saliency-based orienting processes are claimed. Therefore, we developed an endogenous feature-based split-cue task to allow for endogenous saliency-based orienting. IOR was observed in the saliency-driven endogenous cuing condition, and not in the control condition that prevented saliency-based orienting. These results suggest that usage of saliency-based orienting processes in either endogenous or exogenous orienting warrants the appearance of IOR.     

Semantic involvement in the lexical and sentence processing of Japanese kanji

This study examined how skilled Japanese readers activate semantic information when reading kanji compound words at both the lexical and sentence levels. Experiment 1 used a lexical decision task for two-kanji compound words and nonwords. When nonwords were composed of kanji that were semantically similar to the kanji of real words, reaction times were longer and error rates were higher than when nonwords had kanji that were not semantically similar. Experiment 2 used a proofreading task (detection of kanji miscombinations) for the same two-kanji compound words and nonwords at the sentence level. In this task, semantically similar nonwords were detected faster than dissimilar nonwords, but error rates were much higher for the semantically similar nonwords. Experiment 3 used a semantic decision task for sentences with the same two-kanji compound words and nonwords. It took longer to detect semantically similar nonwords than dissimilar nonwords. This indicates that semantic involvement in the processing of Japanese kanji produces different effects, depending on whether this processing is done at the lexical or sentence level, which in turn is related to where the reader's attention lies.     

Links between social information processing in middle childhood and involvement in bullying

The aim of this study was to investigate the way in which bullies, victims, bully/victims, and those not involved process social information. A peer nomination measure of bullying and victimization was administered twice over an interval of one year. The sample consisted of 236 (126 girls and 110 boys) children at the beginning of the study (T1) and 242 children one year later (T2) (mean age: 8 years). To test how children responded when provoked, both spontaneously and after prompting, we used provocation scenarios, and to test their attributional interpretations we used ambiguous scenarios. The results showed that children not involved in bullying responded in an assertive way to provocation more often than bullies and victims, but not more than bully/victims. In general, aggressive answers diminished after prompting and irrelevant answers increased. Appealing for the help of an adult or a peer was the strategy most often chosen. When the intent of the perpetrator was ambiguous, bully/victims attributed more blame, were angrier, and would retaliate more than those not involved. Partly similar results were obtained when stably involved children were compared with those unstably involved. Suggestions for intervention are presented. Aggr. Behav. 29:116–127, 2003. © 2003 Wiley‐Liss, Inc.     

Top-down contingencies in peripheral cuing: The roles of color and location

According to contingent-processing accounts, peripheral cuing effects are due to the cues' inadvertent selection for processing by control settings set up for targets (e.g., C. L. Folk, R. W. Remington, & J. C. Johnston, 1992). Consequently, cues similar to targets should have stronger effects than do dissimilar cues. In the current study, this prediction is confirmed for cue-target combinations similar or dissimilar in the static features of color (Experiments 1-3) and location (Experiment 4), even when both cues and targets share the dynamic feature of abrupt onset. Perceptual priming (Experiment 2) and reallocation of attention did not account for similar-dissimilar differences (Experiments 3 and 4). The results are best explained by top-down-contingent attentional effects of the similar cues. Implications for bottom-up accounts of peripheral cuing effects are discussed. ((c) 2003 APA, all rights reserved)     

Frontal and parietal lobe involvement in the processing of pretence and intention

We assessed whether different processes might be at play during pretence understanding by examining breakdowns of performance in participants with acquired brain damage. In Experiment 1 patients with frontal or parietal lesions and neurologically intact adults were asked to categorize videos of pretend and real actions. In Experiment 2 participants saw three types of videos: real intentional actions, real accidental actions, and pretend actions. In one session they judged whether the actions they saw were intentional or accidental, and in a second session they judged whether the actions were real or pretend. Parietal patients had particular difficulties in the identification of pretend actions, and both parietal and frontal patients were more impaired than controls in understanding the intentional nature of pretence. Analyses of individual patients’ performance revealed that parietal lesions, and in particular lesions to the temporo-parietal junction, impaired the ability to discriminate pretend from real actions. However, this did not necessarily affect the discrimination of intentional from unintentional actions, which instead may be independently disrupted by damage to frontal areas. Moreover, spared ability to discriminate pretend actions from real actions, and intentional actions from accidental actions, did not grant a full conceptual understanding of the intentional nature of pretence. The implications for pretence understanding are discussed.     

Influence of task and input factors on hemispheric involvement in face processing

Two experiments examined the respective role of the cerebral hemispheres in face perception and the nature of their contribution depending on task demands and on the spatial-frequency composition of the stimuli. Sixteen faces of members of the subjects' department were presented as stimuli, with men and women, and professors and nonprofessors being equally represented. In Experiment 1, high-resolution black-and-white photographs of faces were used in three reaction-time tasks: verbal identification, manual membership categorization, and manual male/female categorization, in a within-subject design. Identification and membership categorization were significantly better performed in right-visual-field presentations, whereas the male/female categorization yielded a nonsignificant left-visual-field superiority. In Experiment 2, two versions of the same faces were used: digitized low-pass (0 to 2 cycles/degree of visual angle) and digitized broad-pass (0 to 32 cycles/degree) faces. Broad-pass faces produced the same laterality pattern as in Experiment 1, while low-pass faces were better processed in left-visual-field presentations for all three tasks. The results suggest that the two hemispheres play a role in face perception, and their contribution may vary as a function of the task demands and of the spatial-frequency components of the incoming information.     

Differential cerebral involvement in perceiving Chinese characters: levels of processing approach

Three experiments were designed to determine the accuracy and latency with which right-handed Chinese university students (12 females and 12 males) recognized Chinese characters in the left and right visual half-fields (VHFs). The experiments varied in the "depth" of processing required. Experiment 1 was a lexical decision task in which the configuration of the stimulus (a real Chinese character or the mirror image of a real character) determined whether the grapheme was an actual character. Experiment 2 required phonological processing; i.e., subjects had to decide whether a character (or a foil) matched the sound of an orally presented Chinese character. Experiment 3 required semantic processing; i.e., subjects had to decide if a character (or a foil) belonged to a particular semantic category. In each experiment, single characters were presented unilaterally for 150 msec. There was a significant right VHF superiority for accuracy scores for Experiments 2 and 3 but not for Experiment 1. None of the experiments yielded significant visual asymmetries in reaction time. The results do not support previous claims of orthography-specific laterality, but instead show that laterality effects for morphemic stimuli vary with the orthographic, phonological, and semantic processing demands of the task.     

Direct versus indirect processing changes the influence of color in natural scene categorization

We examined whether participants would use a negative priming (NP) paradigm to categorize color and grayscale images of natural scenes that were presented peripherally and were ignored. We focused on (1) attentional resources allocated to natural scenes and (2) direct versus indirect processing of them. We set up low and high attention-load conditions, based on the set size of the searched stimuli in the prime display (one and five). Participants were required to detect and categorize the target objects in natural scenes in a central visual search task, ignoring peripheral natural images in both the prime and probe displays. The results showed that, irrespective of attention load, NP was observed for color scenes but not for grayscale scenes. We did not observe any effect of color information in central visual search, where participants responded directly to natural scenes. These results indicate that, in a situation in which participants indirectly process natural scenes, color information is critical to object categorization, but when the scenes are processed directly, color information does not contribute to categorization.     

Motion and color processing in school-age children and adults: an ERP study

Stimuli designed to selectively elicit motion or color processing were used in a developmental event-related potential study with adults and children aged 6, 7 and 8. A positivity at posterior site INZ (P-INZ) was greater to motion stimuli only in adults. The P1 and N1 were larger to color stimuli in both adults and children, but earlier to motion stimuli only in adults. Finally, the P2 was larger to color stimuli in adults but larger to motion stimuli in children, and earlier to motion stimuli only in children. The findings across components indicate development from middle childhood to adulthood in aspects of both the motion and color processing systems indexed by this paradigm, but are consistent with an hypothesis of a more protracted time course of development for the motion as compared to the color processing system.     

Central and peripheral cholinergic involvement in the habituation of investigatory head poking in rats

The effects of some centrally and peripherally acting cholinergic agonists and antagonists on locomotor exploration and investigatory head poking were studied in rats. An apparent disruption of within-trials habituation of locomotion and head-poke frequency was demonstrated for arecoline, nicotine, carbachol, scopolamine, and methylscopolamine. It is suggested that the effect may be a consequence of a drug-induced depression of initial activity. When this factor was eliminated, both scopolamine and methylscopolamine showed some slight attenuation of habituation. The increase in head-poke duration over time in controls was blocked by scopolamine; although peripheral factors were involved, the scopolamine effect had a singinficant central component. The results are discussed in relation to hypothetical links between the cholinergic system and habituation.     

Unconscious color priming occurs at stimulus- not percept-dependent levels of processing

Although past studies have shown that visual information can be processed without awareness, the types and levels of this processing have yet to be determined. We used metacontrast masking to explore unconscious priming effects of white, blue, and green stimuli generated on a color video display. We found that a white prime tends to act more like a green than a blue one. Color confusions among unmasked and masked primes and calibrations of the display phosphors show that physical rather than perceptual properties of the stimuli best explain the white prime's effects. We conclude that unconscious color priming in normal observers occurs at early wavelength-dependent levels of processing prior to later color-percept-dependent levels.