Good continuation affects discrimination of visual pattern information in young infants

A familiarization-novelty preference procedure was used to determine whether 3- to 4-month-old and 6- to 7-month-old infants utilize the Gestalt principle of good continuation to organize visual patterns. The study involved presentation of a target item (i.e., a square or diamond) either in-line or off-line with a set of distractor items (i.e., circles). Infants in both age groups responded to a change in the target element in the off-line, but not in the in-line, condition. The results suggest that infants organize visual pattern information in accord with the principle of good continuation. Implications of this finding for models of the ontogenesis and microgenesis of object perception in infants and adults are discussed.     

Motion detection and motion verbs: language affects low-level visual perception

Recent theories propose that semantic representation and sensorimotor processing have a common substrate via simulation. We tested the prediction that comprehension interacts with perception, using a standard psychophysics methodology. While passively listening to verbs that referred to upward or downward motion, and to control verbs that did not refer to motion, 20 subjects performed a motion-detection task, indicating whether or not they saw motion in visual stimuli containing threshold levels of coherent vertical motion. A signal detection analysis revealed that when verbs were directionally incongruent with the motion signal, perceptual sensitivity was impaired. Word comprehension also affected decision criteria and reaction times, but in different ways. The results are discussed with reference to existing explanations of embodied processing and the potential of psychophysical methods for assessing interactions between language and perception.     

Self-directed speech affects visual search performance

People often talk to themselves, yet very little is known about the functions of this self-directed speech. We explore effects of self-directed speech on visual processing by using a visual search task. According to the label feedback hypothesis (Lupyan, 2007a), verbal labels can change ongoing perceptual processing-for example, actually hearing "chair" compared to simply thinking about a chair can temporarily make the visual system a better "chair detector". Participants searched for common objects, while being sometimes asked to speak the target's name aloud. Speaking facilitated search, particularly when there was a strong association between the name and the visual target. As the discrepancy between the name and the target increased, speaking began to impair performance. Together, these results speak to the power of words to modulate ongoing visual processing.     

Self-directed speech affects visual search performance

People often talk to themselves, yet very little is known about the functions of this self-directed speech. We explore effects of self-directed speech on visual processing by using a visual search task. According to the label feedback hypothesis (Lupyan, 2007a), verbal labels can change ongoing perceptual processing—for example, actually hearing “chair” compared to simply thinking about a chair can temporarily make the visual system a better “chair detector”. Participants searched for common objects, while being sometimes asked to speak the target's name aloud. Speaking facilitated search, particularly when there was a strong association between the name and the visual target. As the discrepancy between the name and the target increased, speaking began to impair performance. Together, these results speak to the power of words to modulate ongoing visual processing.     

Food pleasantness affects visual selective attention

Fundamental to adaptive behaviour is the ability to select environmental objects that best satisfy current needs and preferences. Here we investigated whether temporary changes in food preference influence visual selective attention. To this end, we exploited the fact that when a food is eaten to satiety its motivational value and perceived pleasantness decrease relative to other foods not eaten in the meal, an effect termed sensory-specific satiety. A total of 26 hungry participants were fed until sated with one of two palatable foods. Before and after selective satiation, participants rated the pleasantness of the two foods and then viewed the same as stimuli on a computer screen while attention was assessed by a visual probe task. Results showed that the attentional bias for the food eaten decreased markedly from pre- to postsatiety, along with the subjective pleasantness for that food. By contrast, subjective pleasantness and attentional bias for the food not eaten did not show any such decrease. These findings suggest that the allocation of visual selective attention is flexibly and rapidly adjusted to reflect temporary shift in relative preference for different foods.     

Familiarity affects visual processing of words.

While previous research has demonstrated that words can be processed more rapidly and/or more accurately than random strings of letters, it has not been convincingly demonstrated that the superior processing of words is a visual effect. In the present experiment, the cases of letters were manipulated in letter strings that were to be compared on the basis of physical identity. Mean response time was shorter for words than for nonwords even for pairs of letter strings that differed only in case (e.g., site-site). This finding implies that the advantage of words over nonwords (the familiarity effect) typically observed in the simultaneous matching task is not due solely to comparison of either the word names or the letter names and, thus, that at least part of the familiarity effect must be due to more rapid formation and/or comparison of visual representations of the two letter strings when they are words. Further analysis failed to reveal a significant involvement of phonemic or lexical codes in the comparison judgments.     

Attentional bias affects change detection

Thirty smokers and 30 nonsmokers participated in aflicker study in which the role of attentional bias in change detection was examined. The participants observed picture pairs of everyday objects flicker on a computer screen until they detected the one object that had changed. In half of the pictures, a smoking-related object (e.g., a lighter) was included among smoking-unrelated objects (e.g., a spoon). Half of the smokers and half of the nonsmokers were aware of the experiment’s focus, and the other half were not. The smokers exhibited shorter detection latencies than did the nonsmokers when a smoking object changed and longer detection latencies when a nonsmoking object changed while a smoking object was present, and they exhibited detection latencies similar to those of the nonsmokers when smoking objects were not present. Interestingly, the nonsmokers displayed the same attentional bias as the smokers when they were aware of the experiment’s smoking focus, but they did not display any attentional bias when they were unaware. Thus, these findings provide evidence for long-term context-independent, as well as for short-term context-dependent, attentional bias.     

Feature-based memory-driven attentional capture: visual working memory content affects visual attention

In 7 experiments, the authors explored whether visual attention (the ability to select relevant visual information) and visual working memory (the ability to retain relevant visual information) share the same content representations. The presence of singleton distractors interfered more strongly with a visual search task when it was accompanied by an additional memory task. Singleton distractors interfered even more when they were identical or related to the object held in memory, but only when it was difficult to verbalize the memory content. Furthermore, this content-specific interaction occurred for features that were relevant to the memory task but not for irrelevant features of the same object or for once-remembered objects that could be forgotten. Finally, memory-related distractors attracted more eye movements but did not result in longer fixations. The results demonstrate memory-driven attentional capture on the basis of content-specific representations.     

Perceptual continuation and depth in visual phantoms can be explained by perceptual transparency

We try to explain perceptual continuation and depth in the visual-phantom illusion in terms of perceptual transparency. Perceptual continuation of inducing gratings across the occluder in stationary phantoms could be explained with unique transparency, a notion proposed by Anderson (1997 Perception 26 419-453). This view is consistent with a number of previous reports including that of McCourt (1994 Vision Research 34 1609-1617) who criticized the stationary phantom illusion from the viewpoint of his counterphase lightness induction or grating induction, which might involve invalid transparency. Here we confirm that the photopic phantom illusion (Kitaoka et al, 1999 Perception 28 825-834) really gives in-phase lightness induction and involves bistable transparency. It is thus suggested that perceptual continuation and depth in the visual-phantom illusion depend on perceptual transparency.     

Temporal context affects the perceived time of visual events

We investigated whether the moment at which an event is perceived depends on its temporal context. Participants learned a mapping between time and space by watching the hand of a clock rotating a full revolution in a fixed duration. Then the hand was removed, and a target disc was flashed within a fixed-interval duration. Participants were to indicate where the hand would have been at the time of the target. In three separate experiments, we estimated the disruption from a distractor disc that was presented before or after the target disc, with a variable time between them. The target was either revealed at the end of the trial or cued beforehand, and in the latter case, was cued by either color or temporal order. We found an attraction to the presentation time of the distractor when both events were attended equally (target revealed at the end). When the target was cued beforehand, the reported time was under- or overestimated, depending on whether the nature of distractor had to be decoded (precued by color) or not (precued by order). In summary, the perceived time of an event is always affected by other events in temporal proximity, but the nature of this effect depends on how each event is attended.

     

Infants' physical knowledge affects their change detection

Prior research suggests that infants attend to a variable in an event category when they have identified it as relevant for predicting outcomes in the category, and that the age at which infants identify a variable depends largely on the age at which they are exposed to appropriate observations. Thus, depending on age of exposure, infants may identify the same variable at different ages in different event categories. A good case in point is the variable height, which is identified at about 3.5 months in occlusion events, but only at about 12 months in covering events and 14 months in tube events. In the present experiments, 11-month-olds detected a change to an object's height in an occlusion but not a covering event, and 12.5-month-olds detected a similar change in a covering but not a tube event. Thus, infants succeeded in detecting a change to an object's height in an event where height had been identified as a relevant variable, but failed to detect the exact same change in another event where height had not yet been identified as a relevant variable. These findings provide evidence that infants' physical knowledge affects which changes they detect in physical events. Possible mechanisms underlying these findings are also discussed, in light of recent accounts of change detection in adults.     

Reading action word affects the visual perception of biological motion

In the present study, we investigate whether reading an action-word can influence subsequent visual perception of biological motion. The participant's task was to perceptually judge whether a human action identifiable in the biological motion of a point-light display embedded in a high density mask was present or not in the visual sequence, which lasted for 633 ms on average. Prior to the judgement task, participants were exposed to an abstract verb or an action verb for 500 ms, which was related to the human action according to a congruent or incongruent semantic relation. Data analysis showed that correct judgements were not affected by action verbs, whereas a facilitation effect on response time (49 ms on average) was observed when a congruent action verb primed the judgement of biological movements. In relation with the existing literature, this finding suggests that the perception, the planning and the linguistic coding of motor action are subtended by common motor representations.     

Mathematics anxiety affects counting but not subitizing during visual enumeration

Individuals with mathematics anxiety have been found to differ from their non-anxious peers on measures of higher-level mathematical processes, but not simple arithmetic. The current paper examines differences between mathematics anxious and non-mathematics anxious individuals in more basic numerical processing using a visual enumeration task. This task allows for the assessment of two systems of basic number processing: subitizing and counting. Mathematics anxious individuals, relative to non-mathematics anxious individuals, showed a deficit in the counting but not in the subitizing range. Furthermore, working memory was found to mediate this group difference. These findings demonstrate that the problems associated with mathematics anxiety exist at a level more basic than would be predicted from the extant literature.     

Semantic effects in visual word detection with visual similarity controlled

In three experiments, subjects searched through word lists for a single target word. Search was faster when the target word belonged to a different semantic category from that of the background words with visual similarity controlled. This semantic effect increased with number of items to be searched through, and it obtained whether the target was cued visually or verbally. Semantic homogeneity within the background also speeded search, but only when subjects had no prior knowledge of the nature of a list. Several models of the semantic effect are described. All contrast the encoding of physical identity with the encoding of semantic attributes, but they differ in ascribing the effect to: (1) the relative access times for these codes, (2) the power of the codes in dealing with multiple comparisons, or (3) the attentional demands of comparison using different levels of code.     

Body ownership affects visual perception of object size by rescaling the visual representation of external space

Size perception is most often explained by a combination of cues derived from the visual system. However, this traditional cue approach neglects the role of the observer’s body beyond mere visual comparison. In a previous study, we used a full-body illusion to show that objects appear larger and farther away when participants experience a small artificial body as their own and that objects appear smaller and closer when they assume ownership of a large artificial body (“Barbie-doll illusion”; van der Hoort, Guterstam, & Ehrsson, PLoS ONE, 6(5), e20195, 2011). The first aim of the present study was to test the hypothesis that this own-body-size effect is distinct from the role of the seen body as a direct familiar-size cue. To this end, we developed a novel setup that allowed for occlusion of the artificial body during the presentation of test objects. Our results demonstrate that the feeling of ownership of an artificial body can alter the perceived sizes of objects without the need for a visible body. Second, we demonstrate that fixation shifts do not contribute to the own-body-size effect. Third, we show that the effect exists in both peri-personal space and distant extra-personal space. Finally, through a meta-analysis, we demonstrate that the own-body-size effect is independent of and adds to the classical visual familiar-size cue effect. Our results suggest that, by changing body size, the entire spatial layout rescales and new objects are now perceived according to this rescaling, without the need to see the body.     

Spatio-temporal effects in visual gap detection

The ability of the visual system to process temporal information is studied with regard to the interactions between temporal and spatial stimulus dimensions. A comparison of the results of two experiments indicate that the eye is able to discriminate temporal gaps in a train of visual flashes better when the flashes are spatially superposed then when they are dispersed. Thus, the inertial and integrating properties of the visual receptor seem, at first glance, to hinder the discrimination less than does spatial dispersion. However, an analysis of the results, using Levinson’s low-pass filter model, suggests that the increased discrimination is due to the recoding of the temporal stimulus information along a brightness dimension, and thus the true temporal properties of the visual system are probably better described by the dispersed rather than the overlapped condition. Other experiments are also reported that deal with related phenomena germane to the ability of human Ss to deal with the temporal information pattern of visual stimuli.