Color singleton pop-out does not always poop out: An alternative to visual search

Folk psychology suggests that when an observer views a scene, a unique item will stand out and draw attention to itself. This belief stands in contrast to numerous studies in visual search that have found that a unique target item (e.g., a unique color) is not identified more quickly than a nonunique target. We hypothesized that this finding is the result of task demands of visual search, and that when the task does not involve visual search, uniqueness will pop out. We tested this hypothesis in a task in which observers were presented an array of letters and asked to respond aloud, as quickly as possible, with the identity of any one of the letters. The observers were significantly more likely to respond with a uniquely colored letter than would be expected by chance. In a task in which observers blurt out the first thing that they see, unique pop-out does not poop out.     

Action does not resist visual illusions

Recent TICS articles1, 2 discussed the psychophysical evidence in favor of Goodale and Milner's action vs. perception hypothesis³. Carey argued that most of the studies investigating the effects of visual illusions on grasping can be reconciled with the notion that the action system resists visual illusions¹. Bruno suggested a new interpretation of the action vs. perception hypothesis in order to incorporate most of the empirical findings². Here, I argue that action does not resist visual illusions. Even more, the effects on the motor system seem to be comparable to the effects on the perceptual system. This challenges the action vs. perception hypothesis in its current form.     

Ignored visual context does not induce latent learning

Psychonomic Bulletin & Review - People usually become faster at finding a visual target after repeated exposure to the same search display. This effect, known as contextual cueing, is often...     

Social salience does not transfer to oculomotor visual search

ABSTRACT

Evidence suggests that socially relevant information, such as self-referential information, leads to perceptual prioritization that is considered to be similar to prioritization based on physical stimulus salience. The current study used an oculomotor visual search paradigm to investigate whether self-prioritization affects visual selection early in time, akin to physical salience, or later in time, where it would relate to processing of top-down strategies. We report three experiments. Prior to each experiment, observers first performed a manual line-label matching task where they were asked to form associations between two orientation lines (right-tilted and left-tilted) and two labels (“you” and “stranger”). Participants then had to make a speeded eye-movement to one of the two lines without any task instructions (Experiment 1), to a dot probe target located on one of the two lines (Experiment 2), or to the line that was validly cued by its associated label (Experiment 3). We replicate previous findings with the manual stimulus-matching task. However, we did not find any evidence for increased salience of the self-relevant “you” stimulus during visual search, nor did we observe any self-prioritization due to later goal-driven or strategic processing. We argue that self-prioritization does not affect overt visual selection. The results suggest that the effects found in the manual matching task are unlikely to reflect self-prioritization during perceptual processing but might rather act on higher-level processing related to recognition or decision-making.     

Representing visual recursion does not require verbal or motor resources

The ability to form and use recursive representations while processing hierarchical structures has been hypothesized to rely on language abilities. If so, linguistic resources should inevitably be activated while representing recursion in non-linguistic domains. In this study we use a dual-task paradigm to assess whether verbal resources are required to perform a visual recursion task. We tested participants across 4 conditions: (1) Visual recursion only, (2) Visual recursion with motor interference (sequential finger tapping), (3) Visual recursion with verbal interference – low load, and (4) Visual recursion with verbal interference – high load. Our results show that the ability to acquire and use visual recursive representations is not affected by the presence of verbal and motor interference tasks. Our finding that visual recursion can be represented without access to verbal resources suggests that recursion is available independently of language processing abilities.     

Abrupt luminance change pops out; abrupt color change does not

The present studies investigated whether an isoluminant color change pops out, indicating that it can be detected preattentively in parallel. The results of Experiment 1 show that an abrupt color change presented on an equiluminant background does not pop out. However, when the color change is accompanied by a small luminance change, it does pop out. The results of Experiment 2 show that the pop-out is fully due to the luminance change and not to the color change. The results of Experiments 3 and 4 show that the failure to find a pop-out at equiluminance cannot be attributed to the limited temporal resolution for chromatic stimuli. The results of Experiment 5 show that particular search strategies cannot be responsible for the obtained results. The results are in agreement with physiological findings regarding the parvo and magno systems.     

Spatial updating during locomotion does not eliminate viewpoint-dependent visual object processing

Two experiments were conducted to investigate whether locomotion to a novel test view would eliminate viewpoint costs in visual object processing. Participants performed a sequential matching task for object identity or object handedness, using novel 3-D objects displayed in a head-mounted display. To change the test view of the object, the orientation of the object in 3-D space and the test position of the observer were manipulated independently. Participants were more accurate when the test view was the same as the learned view than when the views were different no matter whether the view change of the object was 50° or 90°. With 50° rotations, participants were more accurate at novel test views caused by participants’ locomotion (object stationary) than caused by object rotation (observer stationary) but this difference disappeared when the view change was 90°. These results indicate that facilitation of spatial updating during locomotion occurs within a limited range of viewpoints, but that such facilitation does not eliminate viewpoint costs in visual object processing.     

Cued visual attention does not distinguish between occluded and occluding objects

Does visual attention spread from the cued end of an occluded object to locations occupied by inferred portions of that object? We investigated this question by using a probe detection paradigm with two-dimensional (2-D) displays of occluded objects. Probes could appear in occluded or nonoccluded locations on either a cued or noncued object. Participants responded faster to probes appearing within the region of space occupied by the cued object. This was true not only when the probe appeared in positions separated from the cued location by an occluder (as demonstrated by Moore, Yantis, & Vaughan, 1998), but also when it appeared in positions on the occluder itself. Thus, results suggest that cued facilitation spreads to regions of noncued occluding objects that overlap cued occluded objects in 2-D space.     

Visual mental image generation does not overlap with visual short-term memory: A dual-task interference study

Visual mental imagery and working memory are often assumed to play similar roles in high-order functions, but little is known of their functional relationship. In this study, we investigated whether similar cognitive processes are involved in the generation of visual mental images, in short-term retention of those mental images, and in short-term retention of visual information. Participants encoded and recalled visually or aurally presented sequences of letters under two interference conditions: spatial tapping or irrelevant visual input (IVI). In Experiment 1, spatial tapping selectively interfered with the retention of sequences of letters when participants generated visual mental images from aural presentation of the letter names and when the letters were presented visually. In Experiment 2, encoding of the sequences was disrupted by both interference tasks. However, in Experiment 3, IVI interfered with the generation of the mental images, but not with their retention, whereas spatial tapping was more disruptive during retention than during encoding. Results suggest that the temporary retention of visual mental images and of visual information may be supported by the same visual short-term memory store but that this store is not involved in image generation.     

Target self-relevance speeds visual search responses but does not improve search efficiency

ABSTRACT

In a variety of contexts, arbitrarily associating one’s self with a stimulus improves performance relative to stimuli that are not self-associated, implying enhanced processing of self-associated stimuli (“self-relevance” effects). Self-relevance has been proposed to influence diverse aspects of cognition, including the perceptual prioritization of self-relevant stimuli (“self-prioritization” effects). We sought to elucidate the mechanisms of self-prioritization by using a visual search paradigm. In three experiments, subjects learned two stimulus-label combinations (SELF and OTHER), and then searched for one of those stimuli (cued by the label) on each trial, with a variable number of distractors present on each trial. We hypothesized that, if self-relevance enhances the perceptual salience of the stimuli pre-attentively, then the self-relevance of a target should result in improved search efficiency. In three experiments using conjunction-defined (Experiments 1–2) and feature-defined (Experiment 3) targets, we found that self-relevant targets were associated with overall faster responses than non-self-relevant targets (an intercept effect). However, the slopes of the search size by reaction time (RT) function were never significantly different between the self-relevant and non-self-relevant conditions, counter to the hypothesis that self-prioritization is pre-attentive. These results constitute novel evidence that self-relevance affects visual search performance, but they also cast doubt on the possibility that self-relevance enhances the perceptual salience of a target in a manner similar to physical manipulations. We propose that the self-relevance of a stimulus alters processing only after the self-relevant item has been attended.     

Monocular occlusion impairs stereoscopic acuity,but total visual deprivation does not

Wallach and Karsh (1963) reported that 24 h of monocular occlusion leads to a significant deterioration of stereoscopic depth estimates and attributed this phenomenon to “disuse.” We designed an apparatus for testing stereoscopic accuracy which eliminated all cues to depth save binocular disparity. With it, we tested the relative effect of 8 h of monocular—;as opposed to binocular—;occlusion on subsequent stereoscopic performance. Monocular patching led to significant increases in mean standard deviation and in mean absolute error as compared to baseline testing. Binocular patching led to no such impairment. Thus, truedisuse (such as occurs during binocular deprivation) did not impair stereopsis, whereas monocular occlusion, which may involve temporarymisuse of the stereoscopic system, did.     

When the visual format of the color carrier word does and does not modulate the Stroop effect

We investigated the impact of making the color carrier word visually unfamiliar via case and font mixInG in the context of three Stroop experiments. Experiment 1 yielded an increase in the size of the Stroop effect when the color carrier words were visually unfamiliar relative to lowercase words that were case and font consistent. Experiments 2A and 2B showed that the modulation of the Stroop effect by visual familiarity observed in Experiment 1 was eliminated when there was no correlation between the color and the color carrier word. These results are considered in the light of four different theoretical accounts of the Stroop effect (strength of association [Cohen, Dunbar, & McClelland, 19901, instance [Logan, 1988], schema [MacLeod, 2000], and obligatory processing followed by deactivation [Coltheart, Woollams, Kinoshita, & Perry, 1999]). None of these accounts appear capable of explaining all the results.     

Pip and pop: nonspatial auditory signals improve spatial visual search

Searching for an object within a cluttered, continuously changing environment can be a very time-consuming process. The authors show that a simple auditory pip drastically decreases search times for a synchronized visual object that is normally very difficult to find. This effect occurs even though the pip contains no information on the location or identity of the visual object. The experiments also show that the effect is not due to general alerting (because it does not occur with visual cues), nor is it due to top-down cuing of the visual change (because it still occurs when the pip is synchronized with distractors on the majority of trials). Instead, we propose that the temporal information of the auditory signal is integrated with the visual signal, generating a relatively salient emergent feature that automatically draws attention. Phenomenally, the synchronous pip makes the visual object pop out from its complex environment, providing a direct demonstration of spatially nonspecific sounds affecting competition in spatial visual processing.     

The ventriloquist effect does not depend on the direction of deliberate visual attention

It is well known that discrepancies in the location of synchronized auditory and visual events can lead to mislocalizations of the auditory source, so-called ventriloquism. In two experiments, we tested whether such cross-modal influences on auditory localization depend on deliberate visual attention to the biasing visual event. In Experiment 1, subjects pointed to the apparent source of sounds in the presence or absence of a synchronous peripheral flash. They also monitored for target visual events, either at the location of the peripheral flash or in a central location. Auditory localization was attracted toward the synchronous peripheral flash, but this was unaffected by where deliberate visual attention was directed in the monitoring task. In Experiment 2, bilateral flashes were presented in synchrony with each sound, to provide competing visual attractors. When these visual events were equally salient on the two sides, auditory localization was unaffected by which side subjects monitored for visual targets. When one flash was larger than the other, auditory localization was slightly but reliably attracted toward it, but again regardless of where visual monitoring was required. We conclude that ventriloquism largely reflects automatic sensory interactions, with little or no role for deliberate spatial attention.     

Anuran predators overcome visual illusion: dazzle coloration does not protect moving prey

Predators everywhere impose strong selection pressures on the morphology and behavior of their prey, but the resulting antipredator adaptations vary greatly among species. Studies of adaptive coloration in prey species have generally focused on cryptic or aposematic prey, with little consideration of color patterns in palatable mobile prey. Complex color patterns have been proposed to decrease the ability of visual predators to capture moving prey (motion dazzle effect). Most support for this hypothesis, however, comes from experiments with human subjects and simulated prey. We tested the motion dazzle effect using, for the first time, natural predators (cane toads, Rhinella marina) and live prey (house crickets, Acheta domesticus) with altered color patterns. We found no support for the motion dazzle effect as striped crickets did not fare better than solid colored ones. Crickets that spent more time moving, however, were more likely to be eaten. Our results suggest that motion specialized visual predators such as toads overcome the motion dazzle effect and impose stronger selection pressure on prey behavior than on coloration. These findings emphasize the importance of sensory specializations of predators in mediating antipredator strategies.     

The ventriloquist effect does not depend on the direction of automatic visual attention

Previously, we showed that the visual bias of auditory sound location, or ventriloquism, does not depend on the direction of deliberate, orendogenous, attention (Bertelson, Vroomen, de Gelder, & Driver, 2000). In the present study, a similar question concerning automatic, orexogenous, attention was examined. The experimental manipulation was based on the fact that exogenous visual attention can be attracted toward asingleton—that is, an item different on some dimension from all other items presented simultaneously. A display was used that consisted of a row of four bright squares with one square, in either the left- or the rightmost position,smaller than the others, serving as the singleton. In Experiment 1, subjects made dichotomous left-right judgments concerning sound bursts, whose successivelocations were controlled by a psychophysical staircase procedure and which were presented in synchrony with a display with the singleton either left or right. Results showed that the apparent location of the sound was attractednot toward the singleton, but instead toward the big squares at the opposite end of the display. Experiment 2 was run to check that the singleton effectively attracted exogenous attention. The task was to discriminate target letters presented either on the singleton or on the opposite big square. Performance deteriorated when the target was on the big square opposite the singleton, in comparison with control trials with no singleton, thus showing that the singleton attracted attention away from the target location. In Experiment 3, localization and discrimination trials were mixed randomly so as to control for potential differences in subjects’ strategies in the two preceding experiments. Results were as before, showing that the singleton attracted attention, whereas sound localization was shifted away from the singleton. Ventriloquism can thus be dissociated from exogenous visual attention and appears to reflect sensory interactions with little role for the direction of visual spatial attention.     

The pop out of scene-relative object movement against retinal motion due to self-movement

An object that moves is spotted almost effortlessly; it "pops out". When the observer is stationary, a moving object is uniquely identified by retinal motion. This is not so when the observer is also moving; as the eye travels through space all scene objects change position relative to the eye producing a complicated field of retinal motion. Without the unique identifier of retinal motion an object moving relative to the scene should be difficult to locate. Using a search task, we investigated this proposition. Computer-rendered objects were moved and transformed in a manner consistent with movement of the observer. Despite the complex pattern of retinal motion, objects moving relative to the scene were found to pop out. We suggest the brain uses its sensitivity to optic flow to "stabilise" the scene, allowing the scene-relative movement of an object to be identified.     

Transient stimulation does not aid visual search: Implications for the role of saccades

Previous demonstrations that performance on visual search tasks with briefly flashed presentations declines over time after the initial onset imply that saccades might be necessary for efficient acquisition of visual information. We imposed an additional abrupt onset and a displacement on character arrays containing letters and one numeral while subjects searched for the numeral. Presentations were always followed by a visual noise field. Presentation time varied (50–800 msec). We found that performance with presentations containing one onset and remaining continuously visible was better than performance with presentations containing two onsets and containing displacements. Furthermore, information acquired near the onset of a continuous presentation was as effective as information acquired later. Our results demonstrate that abrupt onsets and displacements do not improve information acquisition with displays of alphanumeric characters. This finding is consistent with earlier reports that saccade-like retinal image motion does not contribute either to the maintenance of target visibility or to visual acuity.     

Imageability does not interact with visual field in lateral word recognition with oral report

Four lateral tachistoscopic experiments are reported which tested the hypothesis that the right hemisphere has a selective ability to process highly imageable words (the RH imageability hypothesis). The prediction that performance asymmetry would vary as a function of word imageability, in a lateral recognition task with oral report, was not fulfilled. Results suggested that several previously published studies which hitherto have been regarded as supporting the RH imageability hypothesis may be discounted on artifactual grounds. The implications of these findings for the overall status of the hypothesis were discussed.