Experience-dependent perceptual grouping and object-based attention.

Earlier studies have shown that attention can be directed to objects, defined on the basis of generic grouping principles, highly familiar shapes, or task instructions, rather than to contiguous regions of the visual field. The 4 experiments presented in this article extend these findings, showing that object attention benefits--shorter reaction times to features appearing on a single object--apply to recently viewed novel shapes. One experiment shows that object attention operates even when the visible fragments correspond to objects that violate standard completion heuristics. Other experiments show that experience-dependent object benefits can apply to fragments even without evidence of occlusion. These results attest to the flexible operation of the perceptual system, adapting as a function of experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial attention does not require preattentive grouping.

Does spatial attention follow a full preattentive analysis of the visual field, or can attention select from ungrouped regions of the visual field? We addressed this question by testing an apperceptive agnosic patient, J. W., in tasks involving both spatial selection and preattentive grouping. Results suggest that J. W. had intact spatial attention: He was faster to detect targets appearing at cued locations relative to targets appearing at uncued locations. However, his preattentive processes were severely disrupted. Gestalt grouping and symmetry perception, both thought to involve preattentive processes, were impaired in J. W. Also, he could not use gestalt grouping cues to guide spatial attention. These results suggest that spatial attention is not completely dependent on preattentive grouping processes. We argue that preattentive grouping processes and spatial attention may mutually constrain one another in guiding the attentional selection of visual stimuli but that these 2 processes are isolated from one another. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conjunction of color and form without attention: Evidence from an orientation-contingent color aftereffect.

According to A. Treisman and G. Gelade's (see record 1980-04685-001) feature-integration theory, separable features such as color and shape exist in separate maps in preattentive vision and can be integrated only through the use of spatial attention. However, many perceptual aftereffects, which are also assumed to reflect the features available in preattentive vision, are sensitive to conjunctions of features. One possible resolution of these views holds that adaptation to conjunctions depends on spatial attention. Exp I tested this proposition by presenting 24 undergraduates with gratings varying in color and orientation. The resulting McCollough aftereffects were independent of whether the adaptation stimuli were presented inside or outside of the focus of spatial attention. Therefore, color and shape appear to be conjoined preattentively when perceptual aftereffects are used as the measure. These same stimuli, however, appeared to be separable in Exps II and III, which required 24 Ss to search for gratings of a specified color and orientation. These results show that different experimental procedures may be tapping into different stages of preattentive vision. (63 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Perception without awareness: Critical issues.

Discusses the conceptual distinction between conscious and unconscious processes and considers problems with measuring conscious perceptual experience. Because of interpretive problems with subjective reports, some investigators prefer to use objective measures to distinguish between aware and nonaware states. However, studies using objective measures have not provided evidence either for or against perception without awareness. Studies are reviewed in which 3 qualitative differences between conscious and unconscious perceptual processes were established. These differences involve predominate code, prediction, and selection. Such demonstrations of qualitative differences in performance across aware and nonaware conditions can both validate measures of awareness and show how conscious and unconscious processes differ. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual word recognition without central attention: Evidence for greater automaticity with advancing age.

The present experiments examined the automaticity of word recognition. The authors examined whether people can recognize words while central attention is devoted to another task and how this ability changes across the life span. In Experiment 1, a lexical decision Task 2 was combined with either an auditory or a visual Task 1. Regardless of the Task 1 modality, Task 2 word recognition proceeded in parallel with Task 1 central operations for older adults but not for younger adults. This is a rare example of improved cognitive processing with advancing age. When Task 2 was nonlexical (Experiment 2), however, there was no evidence for greater parallel processing for older adults. Thus, the processing advantage appears to be restricted to lexical processes. The authors conclude that greater cumulative experience with lexical processing leads to greater automaticity, allowing older adults to more efficiently perform this stage in parallel with another task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Socialization and attentional deficits under focusing and divided attention conditions.

Conducted two studies to test and refine the hypothesis that, when undersocialized individuals focus on events of immediate interest, they allocate too large a proportion of their processing resources to those events and have little attention available for processing other important events. College students who completed the Socialization (So) scale (Gough, 1960) performed visual and auditory tasks simultaneously under conditions favoring the visual task, an equal division of processing resources between the tasks, or both. In both studies, low-So Ss performed relatively poorly on the auditory task under focusing conditions but displayed no primary task advantage and no significant performance deficits under divided attention conditions. These data support the utility of theories relating antisocial behavior to individual differences in allocation of attention. Low-So Ss' unresponsiveness to secondary events is not a simple function of the reallocation of resources to the primary task or a speed–accuracy trade-off. Moreover, under certain conditions, this deficit may disappear, given substantial practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preemption effects in visual search: Evidence for low-level grouping.

Experiments are presented showing that visual search for Mueller-Lyer stimuli is based on complete configurations rather than component segments. Segments easily detected in isolation were difficult to detect when embedded in a configuration, indicating preemption by low-level groups. This preemption--which caused stimulus components to become inaccessible to rapid search--was an all-or-nothing effect and so could serve as a powerful test of grouping. It is shown that these effects are unlikely to be due to blurring by simple spatial filters at early visual levels. It is proposed instead that they are due to more sophisticated processes that rapidly bind contour fragments into spatially extended assemblies. These results support the view that rapid visual search cannot access the primitive elements formed at the earliest stages of visual processing; rather, it can access only higher level, more ecologically relevant structures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective reaching: Evidence for action-centered attention.

Most studies of selective attention briefly present static 2-dimensional stimuli and require arbitrary responses such as verbal naming or a keypress. Many of perceptual-motor interactions with the environment, however, require reaching directly toward an object while ignoring other objects in the scene. A series of experiments examines selective attention in the latter reaching situation. Effects previously observed in the traditional experimental procedures were obtained, suggesting that the models developed (which propose inhibitory mechanisms, for example) apply to ecologically valid situations. Attention accesses action-centered internal representations during such tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mood and memory under natural conditions: Evidence for mood incongruent recall.

The effect of mood on memory was studied under natural conditions in 2 field quasi-experiments. In both, Ss in happy moods recalled autobiographical memories that were more negative than were memories recalled by subjects in bad moods, a phenomenon termed mood incongruent recall. Three subsequent laboratory experiments are reported that suggest that mood incongruent recall is a reliable phenomenon, occurring when subjects are unaware that their moods are relevant to the experiment. Mood incongruent recall is hypothesized to be related to mood regulation. The implications of these findings for the relation between mood and memory, for mood congruent recall, for laboratory mood inductions, and for self-regulation of mood and depression are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessing dissimilarity relations under missing data conditions: Evidence from computer simulations.

The extensive research examining relations between group member dissimilarity and outcome measures has yielded inconsistent results. In the present research, the authors used computer simulations to examine the impact that a methodological feature of such research, participant nonresponse, can have on dissimilarity-outcome relations. Results suggest that using only survey responders to calculate dissimilarity typically results in underestimation of true dissimilarity effects and that these effects can occur even when response rates are high. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic attention does not equal automatic fear: Preferential attention without implicit valence.

Theories of nonassociative fear acquisition hold that humans have an innate predisposition for some fears, such as fear of snakes and spiders. This predisposition may be mediated by an evolved fear module (?hman & Mineka, 2001) that responds to basic perceptual features of threat stimuli by directing attention preferentially and generating an automatic fear response. Visual search and affective priming tasks were used to examine attentional processing and implicit evaluation of snake and spider pictures in participants with different explicit attitudes; controls (n = 25) and snake and spider experts (n = 23). Attentional processing and explicit evaluation were found to diverge; snakes and spiders were preferentially attended to by all participants; however, they were negative only for controls. Implicit evaluations of dangerous and nondangerous snakes and spiders, which have similar perceptual features, differed for expert participants, but not for controls. The authors suggest that although snakes and spiders are preferentially attended to, negative evaluations are not automatically elicited during this processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Goal-directed guidance of attention: Evidence from conjunctive visual search.

Conjunctive visual search is most difficult when distractor types are in equal proportions and gets easier as the proportions diverge (e.g., E. Zohary & S. Hochstein, 1989). This may reflect restriction of search to the feature shared by the target and the less-frequent distractor. Alternatively, such effects could reflect target salience, which varies with distractor ratio. In 2 experiments, 60 participants searched 64-element displays for a conjunctive target among distractors of 2 types in various proportions. Participants were correctly informed (Experiment 1) or misinformed (Experiment 2) about which distractor type would be less frequent on most trials. In both experiments, the distractor-ratio effect was significantly influenced by the information provided to participants. These findings demonstrate the efficacy of top-down information in guiding attention and show that it can be applied flexibly, weighted toward particular target features. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual memory for novel shapes: Implicit coding without attention.

Implicit memory for novel shapes was explored with a negative priming paradigm. The results show that representations of shapes, formed in a single trial and without attention, can last without decrement across 200 intervening trials and with temporal delays of up to a month. No explicit memory of the shapes was available, either immediately or after a delay. There were consistent individual differences in the amount of negative priming shown, and some participants showed only facilitation. There was a trend toward increased facilitation across time, as if the memory of the shape survived longer than an "action tag" attached to it, which specified whether it should be attended or ignored. The results demonstrate a surprising combination of plasticity and permanence in the visual system and suggest that the roles of both attention and repetition may be to ensure voluntary retrievability rather than to form a lasting memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual attention and objects: Evidence for hierarchical coding of location.

In 5 experiments, it was found that judging the relative location of 2 contours was more difficult when they belonged to 2 objects rather than 1. This was observed even when the 1- and 2-object displays were physically identical, with perceptual set determining how many objects they were seen to contain. Such a 2-object cost is consistent with object-based views of attention and with a hierarchical scheme for position coding, whereby object parts are located relative to the position of their parent object. In further experiments, it was shown that in accord with this hierarchical scheme, the relative location of objects could disrupt judgments of the relative location of object parts, but the reverse did not occur. This was found even when the relative position of the parts could be judged more quickly than that of the objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sustained attention under thermal stress.

Discusses the effects of the thermal environment on vigilance. A reinterpretation of early and contemporary studies contradicts the existing notion that vigilance is facilitated in ambient temperatures that exceed a comfortable level. Rather, performance is degraded as thermal homeostasis of the observer is disturbed. Significant breakdown in capability becomes manifest with measurable perturbation to deep body temperature. This assertion requires that conditions induce a dynamic change, as performance is unaffected with no variation in deep body temperature and is facilitated when the observer is established in a static hyperthermic state. An attentional account of this phenomenon is offered that contrasts with previous arousal explanations. (112 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gaze perception requires focused attention: Evidence from an interference task.

The direction of another person's gaze is difficult to ignore when presented at the center of attention. In 6 experiments, perception of unattended gaze was investigated. Participants made directional (left-right) judgments to gazing-face or pointing-hand targets, which were accompanied by a distractor face or hand. Processing of the distractor was assessed via congruency effects on target response times. Congruency effects were found from the direction of distractor hands but not from the direction of distractor gazes (Experiment 1). This pattern persisted even when distractor sizes were increased to compensate for their peripheral presentation (Experiments 2 and 5). In contrast, congruency effects were exerted by profile heads (Experiments 3 and 4). In Experiment 6, isolated eye region distractors produced no congruency effects, even when they were presented near the target. These results suggest that, unlike other facial information, gaze direction cannot be perceived outside the focus of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acetylcholine affects the spatial scale of attention: Evidence from Alzheimer's disease.

Location precues were used to manipulate the spatial scale of attention in visual search for a target in an array of letters in patients with dementia of the Alzheimer type (DAT) and in age-matched older controls. Cue size varied in the amount of spatial precision conferred. Scopolamine, a muscarinic antagonist, decreased overall arousal and broadened spatial attention after a precise precue (small and valid) to target location for DAT patients but not for controls, suggesting a selective effect for attentional impairment induced by cholinergic blockade. In contrast, physostigmine, a cholinesterase inhibitor, did not alter the distribution of spatial attention relative to no-drug baseline testing for patients. Results support a differential role for cholinergic mechanisms in the modulation of the spatial scale of visual attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the locus of visual selection: Evidence from focused attention tasks.

Early and late selection models of attention disagree about whether visual objects are identified before or after selection, with recent evidence of interference from to-be-ignored stimuli favoring late selection over early selection accounts. However, these tests may not have permitted optimal attentional focusing. In 4 experiments subjects identified an attentionally cued target letter embedded among distractors. Only minimal effects of information appearing in to-be-ignored locations were observed. This striking efficiency of selection provides support for early selection theories and calls into question some late selection theories holding that stimuli throughout the display are immediately and fully identified prior to attentional selection. In order to explain the larger pattern of results across a variety of focused- and divided-attention paradigms, a hybrid model is advanced with a flexible locus for visual selection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

3-D Interpolation in Object Perception: Evidence From an Objective Performance Paradigm.

Object perception requires interpolation processes that connect visible regions despite spatial gaps. Some research has suggested that interpolation may be a 3-D process, but objective performance data and evidence about the conditions leading to interpolation are needed. The authors developed an objective performance paradigm for testing 3-D interpolation and tested a new theory of 3-D contour interpolation, termed 3-D relatability. The theory indicates for a given edge which orientations and positions of other edges in space may be connected to it by interpolation. Results of 5 experiments showed that processing of orientation relations in 3-D relatable displays was superior to processing in 3-D nonrelatable displays and that these effects depended on object formation. 3-D interpolation and 3-D relatabilty are discussed in terms of their implications for computational and neural models of object perception, which have typically been based on 2-D-orientation-sensitive units. (PsycINFO Database Record (c) 2010 APA, all rights reserved)