Deeper attentional masking by lateral objects in children with autism

Autism spectrum disorder (ASD) is often associated with a detail-oriented perception and overselective attention in visual tasks, such as visual search and crowding. These results were obtained manipulating exclusively the spatial properties of the stimuli: few is known about the spatio-temporal dynamics of visual processing in ASD. In this study we employed an attentional masking (AM) paradigm comparing children with ASD and IQ-matched typically developing (TD) controls. The AM effect refers to an impaired identification of a target followed by a competitive masking object at different proximities in space and time. We found that ASD and TD groups did not differ in the AM effect provoked by the competitive object displayed in the same position of the target. In contrast, children with ASD showed a deeper and prolonged interference than the TD group when the masking object was displayed in the lateral position. These psychophysical results suggest that the inefficient attentional selection in ASD depends on the spatio-temporal interaction between competitive visual objects. These evidence are discussed in the light of the ASD altered neural connectivity hypothesis and the reentrant theory of perception.     

The influence of a salient distractor in object-substitution masking

It remains unclear whether a salient distractor directly affects performance accuracy and the perceptual resolution of a target. In order to investigate this issue, the present study employed object substitution masking (OSM) to index perceptual hypothesis testing of a target. Trailing-mask duration of the four-dot mask was varied to investigate how the representation of the masked target decayed over time. Participants responded to the presence of a vertical line on a target ring that was isolated by a four-dot mask while an irrelevant salient distractor was presented in a subset of trials. The results revealed that the salient distractor only impacted performance when the mask and target offset concurrently (Experiment 1) or at short mask durations (Experiment 2). At longer mask durations performance in the distractor present condition was identical to performance in the distractor absent condition, suggesting that involuntary capture of attention did not affect OSM. These results show that the perceptual resolution of a masked target can operate independently of involuntary attentional selection.     

Attention to distinguishing features in object recognition

This study advances the hypothesis that, in the course of object recognition, attention is directed to distinguishing features: visual information that is diagnostic of object identity in a specific context. In five experiments, observers performed an object categorization task involving drawings of fish (Experiments 1–4) and photographs of natural sea animals (Experiment 5). Allocation of attention to distinguishing and non-distinguishing features was examined using primed-matching (Experiment 1) and visual probe (Experiments 2, 4, 5) methods, and manipulated by spatial precuing (Experiment 3). Converging results indicated that in performing the object categorization task, attention was allocated to the distinguishing features in a context-dependent manner, and that such allocation facilitated performance. Based on the view that object recognition, like categorization, is essentially a process of discrimination between probable alternatives, the implications of the findings for the role of attention to distinguishing features in object recognition are discussed.     

The properties of object representations constructed during visual search in natural scenes

To investigate properties of object representations constructed during a visual search task, we manipulated the proportion of trials/task within a block: In a search-frequent block, 80% of trials were search tasks; remaining trials presented a memory task; in a memory-frequent block, this proportion was reversed. In the search task, participants searched for a toy car (Experiments 1 and 2) or a T-shape object (Experiment 3). In the memory task, participants had to memorize objects in a scene. Memory performance was worse in the search-frequent block than in the memory-frequent block in Experiments 1 and 3, but not in Experiment 2 (token change in Experiment 1; type change in Experiments 2 and 3). Experiment 4 demonstrated that lower performance in the search-frequent block was not due to eye-movement behaviour. Results suggest that object representations constructed during visual search are different from those constructed during memorization and they are modulated by type of target.     

See an object,hear an object file: Object correspondence transcends sensory modality

An important task of perceptual processing is to parse incoming information into distinct units and to keep track of those units over time as the same, persisting representations. Within the study of visual perception, maintaining such persisting object representations is helped by “object files”—episodic representations that store (and update) information about objects' properties and track objects over time and motion via spatiotemporal information. Although object files are typically discussed as visual, here we demonstrate that object–file correspondence can be computed across sensory modalities. An object file can be initially formed with visual input and later accessed with corresponding auditory information, suggesting that object files may be able to operate at a multimodal level of perceptual processing.     

Converging evidence of configural processing of faces in high-functioning adults with autism spectrum disorders

There is conflicting evidence about whether individuals with autism spectrum disorder (ASD) demonstrate configural processing of faces. We examined two types of configural processing of unfamiliar faces in high-functioning adults with ASD: Holistic processing (processing a face as a gestalt percept) and processing of second-order relations (the spatial relations among facial features, e.g., distance between two eyes). Compared to age- and IQ-matched typical adults, 17 adults with ASD demonstrated normal holistic processing (as demonstrated by the composite face effect), normal sensitivity to second-order relations in upright faces, and the expected disruption of sensitivity to second-order relations in inverted faces. They were also normal in using the internal features and shape of the external contour to make same/different judgements about facial identity. The results provide converging evidence of configural processing of unfamiliar faces in high-functioning adults with ASD, and bring into question the generalizability of previous reports of abnormal face processing in individuals with ASD.     

Implicit and explicit object recognition at very large visual eccentricities: No improvement after loss of central vision

Little is known about the ability of human observers to process objects in the far periphery of their visual field and nothing about its evolution in case of central vision loss. We investigated implicit and explicit recognition at two large visual eccentricities. Pictures of objects were centred at 30° or 50° eccentricity. Implicit recognition was tested through a priming paradigm. Participants (normally sighted observers and people with 10–20 years of central vision loss) categorized pictures as animal/transport both in a study phase (Block 1) and in a test phase (Block 2). In explicit recognition participants decided for each picture presented in Block 2 whether it had been displayed in Block 1 (“yes”/“no”). Both visual (identical) and conceptual/lexical (same-name) priming occurred at 30° and at 50°. Explicit recognition was observed only at 30°. In people with central vision loss testing was only performed at 50° eccentricity. The pattern of results was similar to that of normally sighted observers but global performance was lower. The results suggest that vision, at large eccentricity, is mainly based on nonconscious coarse representations. Moreover, after 10–20 years of central vision loss, no evidence was found for an increased ability to use peripheral information in object recognition.     

Episodic representation of diagnostic and nondiagnostic object colour

In three experiments, we investigated transsaccadic object file representations. In each experiment, participants moved their eyes from a central fixation cross to a saccade target located between two peripheral objects. During the saccade, this preview display was replaced with a target display containing a single object to be named. On trials in which the target identity matched one of the preview objects, its colour either matched or did not match the previewed object colour. The results indicated that colour changes disrupt perceptual continuity, but only for the class of objects for which colour is diagnostic of object identity. When the colour is not integral to identifying an object (for example, when the object is a letter or an object without a characteristic colour), object continuity is preserved regardless of changes to the object's colour. These results suggest that object features that are important for defining the object are incorporated into its episodic representation. Furthermore, the results are consistent with previous work showing that the quality of a feature's representation determines its importance in preserving continuity.     

Independent effects of colour on object identification and memory

We examined the effects of colour on object identification and memory using a study–test priming procedure with a coloured-object decision task at test (i.e., deciding whether an object is correctly coloured). Objects were selected to have a single associated colour and were either correctly or incorrectly coloured. In addition, object shape and colour were either spatially integrated (i.e., colour fell on the object surface) or spatially separated (i.e., colour formed the background to the object). Transforming the colour of an object from study to test (e.g., from a yellow banana to a purple banana) reduced priming of response times, as compared to when the object was untransformed. This utilization of colour information in object memory was not contingent upon colour falling on the object surface or whether the resulting configuration was of a correctly or incorrectly coloured object. In addition, we observed independent effects of colour on response times, whereby coloured-object decisions were more efficient for correctly than for incorrectly coloured objects but only when colour fell on the object surface. These findings provide evidence for two distinct mechanisms of shape–colour binding in object processing.     

Coding categorical and coordinate spatial relations in visual–spatial short-term memory

Four experiments explored the coding of categorical and coordinate spatial relations in visual–spatial short-term memory (VSSTM). Participants judged whether two stimuli presented successively on a computer screen were the same or different. On positional change trials the two stimuli differed in the position of one element. Positional changes were of two types, coordinate and categorical. On coordinate trials the position of one element changed by a small amount, but retained the categorical relationships (above, below, left of, right of) to all other elements. On categorical trials one element moved by the same amount but additionally changed its categorical relationship to one of the other elements (e.g., changed from below to above). Participants detected categorical changes more accurately than coordinate changes when the elements were independent locations marked by squares, indicating that the categorical relationships amongst the squares were encoded in memory. Furthermore, this categorical advantage was unmodulated by either the suppression of articulation (Experiment 2) or by the requirement to retain either colour–position associations or positions only (Experiment 3). When the elements to be remembered were the vertices of simple outline polygons (Experiment 4) there was no categorical advantage, establishing the effect as spatial in nature. Contrary to predictions derived from Postma and De Haan (1996) Postma, A. and De Haan, E. H. 1996. What was where? Memory for object locations. Quarterly Journal of Experimental Psychology, 49A: 178–199. [Crossref], [Web of Science ®] , [Google Scholar], the employment of categorical relations appears not to be specifically linked to either verbal coding or to the requirement to associate objects with positions. The results suggest that the categorical relations are an intrinsic property of the representation of spatial configurations.