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.     

Dynamic orientation cues decrease the viewpoint cost of mental rotation

Mental rotation, as a covert simulation of motor rotation, could benefit from spatial updating of object representations. We are interested in what kind of visual cue could trigger spatial updating. Three experiments were conducted to examine the effect of dynamic and static orientation cues on mental rotation, using a sequential matching task with three-dimensional novel objects presented in different views. Experiment 1 showed that a rotating orientation cue with constant speed reduced viewpoint costs in mental rotation. Experiment 2 extended this effect with a varied-speed rotating orientation cue. However, no such benefit was observed with a static orientation cue in Experiment 3. These findings indicated that a visually continuous orientation cue is sufficient to elicit spatial updating in mental rotation. Furthermore, there may be differences in the underlying mechanisms of spatial updating on the basis of constant-speed rotating cues and varied-speed rotating cues.     

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.     

No templates for rejection: a failure to configure attention to ignore task-irrelevant features

ABSTRACT

Knowing the colour of an upcoming target allows one to bias attention towards objects of that colour. It is far less clear whether knowing the colour of an up-coming distractor can allow one to suppress attention to items of that colour. Arita, Carlisle, and Woodman (2012) suggest that people can create a template for rejection. However, the method used in Arita et al. may have allowed people to adopt a strategy of internally generating a positive cue for the target colour or target hemifield. Here we use a method very similar to theirs, but manipulate the display layouts and the number of un-cued colours in ways that should thwart such strategies. Across three experiments, we find a negative cuing benefit only in a very special circumstance that encourages a strategic shift to internally generating a positive cue (the same circumstance used by Arita et al.). We conclude that people are unable to use a negative feature-cue on a trial-by-trial basis to suppress attention to upcoming distractors, and attribute the finding in Arita et al. to a strategic shift rather than a template for rejection.     

Mind-reading without the scanner: Behavioural decoding of working memory content

ABSTRACT

Sophisticated machine learning algorithms have been successfully applied to functional neuroimaging data in order to characterize internal cognitive states. But is it possible to “mind-read” without the scanner? Capitalizing on the robust finding that the contents of working memory guide visual attention toward memory-matching objects, we trained a multivariate pattern classifier on behavioural indices of attentional guidance. Working memory representations were successfully decoded from behaviour alone, both within and between individuals. The current study provides a proof-of-concept for applying machine learning techniques to simple behavioural outputs (e.g., response times) in order to decode information about specific internal cognitive states.     

Satisfaction at last: Evidence for the “satisfaction” hypothesis for multiple-target search errors

ABSTRACT

Multiple-target visual searches are susceptible to Subsequent Search Miss (SSM) errors—a reduced accuracy for target detection after a previous target has already been detected. SSM errors occur in critical searches (e.g., evaluations of radiographs and airport luggage x-rays), and have proven to be a stubborn problem. A few SSM theories have been offered, and here we investigate the “satisfaction” account: failing to completely finish a search after having found a first target. Accuracy on a multiple-target search task was compared to both how long participants spent searching after finding a first target and their target sensitivity in a separate vigilance task. Less time spent searching and poor vigilance predicted higher SSM error rates. These results suggest that observers who are more likely to miss a second target are less likely to thoroughly search after finding a first target, thus offering some of the first evidence for the “satisfaction” account.     

Categorical target templates: Typical category members are found and identified quickly during word-cued search

What information do people use to guide search when they lack precise details about the appearance of their target? In this study, we employed categorical (word-cued) search and eye tracking, to examine how category typicality influences search performance. We found that typical category members were fixated and identified more quickly than atypical categories. This finding held when the participant was cued at the superordinate level (finding “clothing” among non-clothing items) or the basic level (finding a “shirt” among other clothing items). This suggests that categorical target templates may be constructed by piecing together features from the most typical category member(s).     

A reversal of the search asymmetry favouring negative schematic faces

Quite a number of studies have tested whether the affective valence of stimuli can guide attention in visual search. Studies using schematic affective faces frequently found a relative search asymmetry (RSA), with more efficient search for a negative face in a friendly crowd than vice versa. Whether, however, this effect relates to differences in affect or to the confounded differences in perceptual features is unknown. The present study proposes and tests a similarity-based account for the RSA. Experiments 1a and 1b first replicate the typical RSA. Experiment 2 shows that the stimulus could be simplified to some degree without losing the RSA. Experiments 3 and 4, finally, demonstrate that the RSA could be reversed by a rather simple stimulus change, that leaves the facial expression intact. It is concluded that the strong dependence of the RSA on stimulus factors seriously questions the claim that emotional factors drive the RSA.     

Failure to exploit learned spatial value information during visual search

ABSTRACT

In recent years there has been rapid proliferation of studies demonstrating how reward learning guides visual search. However, most of these studies have focused on feature-based reward, and there has been scant evidence supporting the learning of space-based reward. We raise the possibility that the visual search apparatus is impenetrable to spatial value contingencies, even when such contingencies are learned and represented online in a separate knowledge domain. In three experiments, we interleaved a visual choice task with a visual search task in which one display quadrant produced greater monetary rewards than the remaining quadrants. We found that participants consistently exploited this spatial value contingency during the choice task but not during the search task – even when these tasks were interleaved within the same trials and when rewards were contingent on response speed. These results suggest that the expression of spatial value information is task specific and that the visual search apparatus could be impenetrable to spatial reward information. Such findings are consistent with an evolutionary framework in which the search apparatus has little to gain from spatial value information in most real world situations.     

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.