Do ability-performance relationships differentiate age and practice effects in visual search?

Investigated relationships between abilities and performance in visual search for 70 young (aged 17–31 yrs) and 70 old adults (aged 65–80 yrs). Ss received extensive practice on a category search task. A consistent version allowed development of an automatic attention response; a varied version allowed general performance improvements. Transfer conditions assessed learning. General ability, induction, semantic knowledge, working memory, perceptual speed, semantic memory access, and psychomotor speed were assessed. LISREL models revealed that general ability and semantic memory access predicted initial performance for both age groups. Improvements on both the consistent and the varied tasks were predicted by perceptual speed. Ability–performance relationships indexed performance changes but were not predictive of learning (i.e., automatic process vs general efficiency). Qualitative differences in the ability-transfer models suggest age differences in learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search asymmetries within color-coded and intensity-coded displays.

Color and intensity coding provide perceptual cues to segregate categories of objects within a visual display, allowing operators to search more efficiently for needed information. Even within a perceptually distinct subset of display elements, however, it may often be useful to prioritize items representing urgent or task-critical information. The design of symbology to produce search asymmetries (Treisman & Souther, 1985) offers a potential technique for doing this, but it is not obvious from existing models of search that an asymmetry observed in the absence of extraneous visual stimuli will persist within a complex color- or intensity-coded display. To address this issue, in the current study we measured the strength of a visual search asymmetry within displays containing color- or intensity-coded extraneous items. The asymmetry persisted strongly in the presence of extraneous items that were drawn in a different color (Experiment 1) or a lower contrast (Experiment 2) than the search-relevant items, with the targets favored by the search asymmetry producing highly efficient search. The asymmetry was attenuated but not eliminated when extraneous items were drawn in a higher contrast than search-relevant items (Experiment 3). Results imply that the coding of symbology to exploit visual search asymmetries can facilitate visual search for high-priority items even within color- or intensity-coded displays. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory-phonetic projection and lexical structure in the recognition of sine-wave words.

Speech remains intelligible despite the elimination of canonical acoustic correlates of phonemes from the spectrum. A portion of this perceptual flexibility can be attributed to modulation sensitivity in the auditory-to-phonetic projection, although signal-independent properties of lexical neighborhoods also affect intelligibility in utterances composed of words. Three tests were conducted to estimate the effects of exposure to natural and sine-wave samples of speech in this kind of perceptual versatility. First, sine-wave versions of the easy and hard word sets were created, modeled on the speech samples of a single talker. The performance difference in recognition of easy and hard words was used to index the perceptual reliance on signal-independent properties of lexical contrasts. Second, several kinds of exposure produced familiarity with an aspect of sine-wave speech: (a) sine-wave sentences modeled on the same talker; (b) sine-wave sentences modeled on a different talker, to create familiarity with a sine-wave carrier; and (c) natural sentences spoken by the same talker, to create familiarity with the idiolect expressed in the sine-wave words. Recognition performance with both easy and hard sine-wave words improved after exposure only to sine-wave sentences modeled on the same talker. Third, a control test showed that signal-independent uncertainty is a plausible cause of differences in recognition of easy and hard sine-wave words. The conditions of beneficial exposure reveal the specificity of attention underlying versatility in speech perception. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

True or false: Do 5-year-olds understand belief?

In 3 studies (N = 188) we tested the hypothesis that children use a perceptual access approach to reason about mental states before they understand beliefs. The perceptual access hypothesis predicts a U-shaped developmental pattern of performance in true belief tasks, in which 3-year-olds who reason about reality should succeed, 4- to 5-year-olds who use perceptual access reasoning should fail, and older children who use belief reasoning should succeed. The results of Study 1 revealed the predicted pattern in 2 different true belief tasks. The results of Study 2 disconfirmed several alternate explanations based on possible pragmatic and inhibitory demands of the true belief tasks. In Study 3, we compared 2 methods of classifying individuals according to which 1 of the 3 reasoning strategies (reality reasoning, perceptual access reasoning, belief reasoning) they used. The 2 methods gave converging results. Both methods indicated that the majority of children used the same approach across tasks and that it was not until after 6 years of age that most children reasoned about beliefs. We conclude that because most prior studies have failed to detect young children's use of perceptual access reasoning, they have overestimated their understanding of false beliefs. We outline several theoretical implications that follow from the perceptual access hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetries in visual search for conjunctive targets.

Asymmetry is demonstrated between conjunctive targets in visual search with no detectable asymmetries between the individual features that compose these targets. Exp 1 demonstrates this phenomenon for targets composed of color and shape. Exps 2 and 4 demonstrate this asymmetry for targets composed of size and orientation and for targets composed of contrast level and orientation, respectively. Exp 3 demonstrates that search rate of individual features cannot predict search rate for conjunctive targets. These results demonstrate the need for 2 levels of representations: one of features and one of conjunction of features. A model related to the modified feature integration theory is proposed to account for these results. The proposed model and other models of visual search are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Similarity neighborhoods of spoken two-syllable words: Retroactive effects on multiple activation.

Investigated the influence of individual syllables in 2-syllable words on the recognition of each other. Specifically, perceptual identification of 2-syllable words comprised of 2 monosyllabic words (spondees) was examined. Individual syllables in a spondee were characterized as either easy or hard, depending on the syllable's neighborhood characteristics; an easy syllable was a high-frequency word in a sparse neighborhood of low-frequency words, and a hard syllable was a low-frequency word in a high-density, high-frequency neighborhood. In Exp 1, stimuli were created by splicing together recordings of component syllables of the spondee, thus equating for syllable stress. Additional experiments tested the perceptual identification of naturally produced spondees, spliced nonwords, and monosyllables alone. Neighborhood structure strongly affected identification in all experiments. Identification performance for spondees with a hard–easy syllable pattern was higher than for spondees with an easy–hard syllable pattern, indicating a primarily retroactive pattern of influence in spoken word recognition. Results strongly suggest that word recognition involves multiple activation and delayed commitment, thus ensuring accurate and efficient recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of stimulus variability on speech perception in listeners with hearing impairment

Traditional word-recognition tests typically use phonetically balanced (PB) word lists produced by one talker at one speaking rate. Intelligibility measures based on these tests may not adequately evaluate the perceptual processes used to perceive speech under more natural listening conditions involving many sources of stimulus variability. The purpose of this study was to examine the influence of stimulus variability and lexical difficulty on the speech-perception abilities of 17 adults with mild-to-moderate hearing loss. The effects of stimulus variability were studied by comparing word-identification performance in single-talker versus multiple-talker conditions and at different speaking rates. Lexical difficulty was assessed by comparing recognition of "easy" words (i.e., words that occur frequently and have few phonemically similar neighbors) with "hard" words (i.e., words that occur infrequently and have many similar neighbors). Subjects also completed a 20-item questionnaire to rate their speech understanding abilities in daily listening situations. Both sources of stimulus variability produced significant effects on speech intelligibility. Identification scores were poorer in the multiple-talker condition than in the single-talker condition, and word-recognition performance decreased as speaking rate increased. Lexical effects on speech intelligibility were also observed. Word-recognition performance was significantly higher for lexically easy words than lexically hard words. Finally, word-recognition performance was correlated with scores on the self-report questionnaire rating speech understanding under natural listening conditions. The pattern of results suggest that perceptually robust speech-discrimination tests are able to assess several underlying aspects of speech perception in the laboratory and clinic that appear to generalize to conditions encountered in natural listening situations where the listener is faced with many different sources of stimulus variability. That is, word-recognition performance measured under conditions where the talker varied from trial to trial was better correlated with self-reports of listening ability than was performance in a single-talker condition where variability was constrained.     

What's in a location? Comparing object-based and space-based models of feature integration in visual search.

What is the unit of selection for feature integration in visual search: location or perceptual object? Feature integration theory (A. Treisman, 1988) asserts that it is location. Two alternative models are put forward and tested in a series of 4 experiments using a special conjunctive search task In this task, each stimulus item consists of 2 overlapping forms (perceptual objects). In general, the search was more efficient when the search features were linked to the same perceptual object than when they were linked to different perceptual objects at the same stimulus location. This same-object advantage, however, was shown to depend on stimulus discriminability and density, grouping strength, and hierarchical object structure. The results support a hierarchical object-based model, with important implications for feature integration, visual search, late versus early selection, and object-based versus space-based views of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual load alters visual excitability.

Increasing perceptual load reduces the processing of visual stimuli outside the focus of attention, but the mechanism underlying these effects remains unclear. Here we tested an account attributing the effects of perceptual load to modulations of visual cortex excitability. In contrast to stimulus competition accounts, which propose that load should affect simultaneous, but not sequential, stimulus presentations, the visual excitability account makes the novel prediction that load should affect detection sensitivity for both simultaneous and sequential presentations. Participants fixated a stimulus stream, responding to targets defined by either a color (low load) or color and orientation conjunctions (high load). Additionally, detection sensitivity was measured for a peripheral critical stimulus (CS) presented occasionally. Increasing load at fixation reduced sensitivity to the peripheral CSs; this effect was similar regardless of whether CSs were presented simultaneously with central stimuli or during the (otherwise empty) interval between them. Controls ruled out explanations of the results in terms of strategic task prioritization. These findings support a cortical excitability account for perceptual load, challenging stimulus competition accounts. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Independent processing across spatial frequency in moving broadband patterns

The aim of the experiments was to discover whether the visual system has independent access to motion information at different spatial scales when presented with a broadband stimulus. Subjects were required to discriminate between a pair of two-frame motion sequences, one containing a coherently displacing pattern and the other containing a pattern with high-frequency noise. The stimuli were either narrowband (1 octave) or broadband (6 octaves spanning 0.23-15.0 cycles deg-1) and their power spectra were either flat or followed a 1/f2 function. For the broadband stimuli, noise was introduced cumulatively into increasingly lower frequencies. For the narrowband stimuli, noise was introduced into the same frequency band as the signal. All stimuli could be defined by the lowest noise frequency (nl) they contained. For each stimulus, the largest spatial displacement across the two frames at which the task could be performed was measured (dmax). For the narrowband stimuli, dmax increased as nl was lowered. This was true over the entire frequency range for the 1/f2 stimuli, though the task became impossible for the flat-spectrum stimuli at the lowest frequencies. This is attributed to the very low contrast of these latter stimuli. The dmax values for the broadband stimuli tended to shadow those of the narrowband stimuli with the equivalent values of nl being around 25% lower. The data were modelled by spatiotemporally filtering the stimuli and considering the amount of directional power in the signal and noise sequences. The results suggest that there must be multiple spatial-frequency channels in operation, and that for broadband patterns the visual system has perceptual access to these individual channel outputs, utilising different filters depending on the task requirements.     

Attentional consequences of object appearance and disappearance.

This study compared the attentional effects of object appearances (onsets) and disappearances (offsets) in moderately complex displays. Four experiments showed that onsets produce the inhibition of return (IOR) effect that has been found with simpler displays. In contrast, although offsets did produce inhibitory effects, these effects did not follow the spatial or temporal pattern of IOR. Two further experiments used a very salient object disappearance to determine whether the typical pattern for IOR could be instantiated; it was not. The results indicate that object appearances are more potent perceptual events than object disappearances. In addition, object disappearances have different attentional consequences than object appearances: Disappearances provoke earlier and spatially narrower inhibition. The results are consistent with the view that inhibition serves a functional role in increasing the efficiency of visual search processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory enhances visual perception: Evidence from signal detection analysis.

We show that perceptual sensitivity to visual stimuli can be modulated by matches between the contents of working memory (WM) and stimuli in the visual field. Observers were presented with an object cue (to hold in WM or to merely attend) and subsequently had to identify a brief target presented within a colored shape. The cue could be re-presented in the display, where it surrounded either the target (on valid trials) or a distractor (on invalid trials). Perceptual identification of the target, as indexed by A′, was enhanced on valid relative to invalid trials but only when the cue was kept in WM. There was minimal effect of the cue when it was merely attended and not kept in WM. Verbal cues were as effective as visual cues at modulating perceptual identification, and the effects were independent of the effects of target saliency. Matches to the contents of WM influenced perceptual sensitivity even under conditions that minimized competition for selecting the target. WM cues were also effective when targets were less likely to fall in a repeated WM stimulus than in other stimuli in the search display. There were no effects of WM on decisional criteria, in contrast to sensitivity. The findings suggest that reentrant feedback from WM can affect early stages of perceptual processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental differences in implicit and explicit memory performance

Performance of preschool, elementary school, and college students was compared on a series of perceptual and conceptual implicit and explicit memory tasks that followed perceptual or conceptual processing during study. As expected, performance on the conceptual explicit memory task improved across age groups. In contrast, performance on the perceptual explicit memory task as well as that on both types of implicit memory tasks showed no developmental change. Also, perceptual processing during study led to better memory performance than conceptual processing for both the perceptual implicit and perceptual explicit tasks and conceptual processing during study led to better memory performance on the conceptual explicit memory task. Performance on the conceptual implicit memory task, in contrast, was affected equally by both types of study processing. The results are discussed in terms of transfer-appropriate processing (Roediger & Blaxton, 1987b) and unitization and grouping processes (Graf & Schacter, 1989).     

Aging and distraction by highly familiar stimuli during visual search.

P. Rabbitt's (1965, 1968) theory regarding age-related changes in cognition proposes that aging is accompanied by a decreased ability to ignore irrelevant information (perceptual noise). The present experiment examined age differences in the extent to which highly familiar stimuli used as perceptual noise could disrupt visual search performance. On Days 1–4, 10 Ss aged 19–27 yrs and 10 Ss aged 63–77 yrs performed a search task with specific, unchanging sets of target and nontarget stimuli (letters). Performance on a subsequent search task (Day 5) was disrupted when these familiar stimuli appeared as noise items in the displays, as compared with trials on which only new, unpracticed stimuli were used. The magnitude of the distraction associated with the familiar stimuli on Day 5 was equivalent for the 2 age groups. However, age differences in Day 5 search performance increased as more items in the simulus display required inspection. Age differences were thus influenced more by the requirement to attend to relevant information than by distraction from irrelevant information. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective Attention Impairments in Alzheimer's Disease: Evidence for Dissociable Components.

Tasks emphasizing 3 different aspects of selective attention-inhibition, visuospatial selective attention, and decision making-were administered to subjects with mild Alzheimer's disease (AD) and to healthy elderly control (HEC) subjects to determine which components of selective attention were impaired in AD subjects and whether selective attention could be dissociated into different components. The tasks were administered with easy versus hard levels of difficulty to assess proportional slowing as the key variable across tasks. The results indicated that the inhibitory and visual search tasks showed greater proportional slowing in subjects with AD than in HEC subjects, and that the task involving inhibition was significantly more affected in subjects with AD. Furthermore, there were no significant intertask correlations, and the results cannot be explained simply in terms of generalized cognitive slowing. These results provide evidence that inhibition is the most strikingly affected aspect of selective attention that is observed to be impaired in early stages of AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual grouping and spatial distortion: A developmental study.

20 Ss in each of 5 age groups (kindergartners; 2nd, 4th, and 6th graders; and graduate students) estimated distances between elements in patterns illustrating the Gestalt grouping principles of proximity, similarity, closure, and good continuation. Ss of all age groups consistently judged distances between elements in the same perceptual group as smaller than physically identical distances between elements in different perceptual groups, which indicated that all Ss were sensitive to the structure of the Gestalt patterns. The magnitude of these distance distortions decreased significantly with age, which suggests that perceptual development includes improvements in the ability to disregard Gestalt groupings when the task requires selective attention to certain elements. Results are consistent with evidence that perceptual development moves from visual processing based primarily on global attributes of patterns to processing that can selectively analyze the component structure of patterns. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related changes in selective attention and perceptual load during visual search.

Three visual search experiments were conducted to test the hypothesis that age differences in selective attention vary as a function of perceptual load (E. A. Maylor & N. Lavie, 1998). Under resource-limited conditions (Experiments 1 and 2), the distraction from irrelevant display items generally decreased as display size (perceptual load) increased. This perceptual load effect was similar for younger and older adults, contrary to the findings of Maylor and Lavie. Distraction at low perceptual loads appeared to reflect both general and specific inhibitory mechanisms. Under more data-limited conditions (Experiment 3), an age-related decline in selective attention was evident, but the age difference was not attributable to capacity limitations as predicted by the perceptual load theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial attention and the apprehension of spatial relations.

Seven experiments examined the role of spatial attention in apprehending spatial relations above, below, left, and right. In Exp 1, visual search was difficult when targets differed from distractors only in the spatial relation between their elements. Reaction time (RT) increased linearly with display size with a slope greater than 60 msec/item. In Exp 2, search was easy (the slope was flat) when targets differed from distractors in the identity of their elements. In Exps 3 and 4, target position was cued with a discrepant color, and performance was better when attention was pulled toward spatial-relation targets than away from them. Exps 5–7 generalized the results over different displays and extended practice. The results suggest that apprehending spatial relations requires spatial attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal limitations in the effective binding of attended target attributes in the mutual masking of visual objects.

The problem of feature binding has been examined under conditions of distributed attention or with spatially dispersed stimuli. We studied binding by asking whether selective attention to a feature of a masked object enables perceptual access to the other features of that object using conditions in which spatial attention was directed at a single location where all objects appeared. In an identification condition, the task required reporting the same property of each object. High rates of identification showed good perceptual availability. In a search condition, the task required reporting the property (e.g., shape) that was associated with a specific value of the searched property (e.g., surface texture) of the same object. Focusing of attention on a target’s searched property value did not result in a high rate of identifying the target’s other property, and strong object masking was found. Backward masking between spatially superimposed visual objects appears to be primarily due to a difficulty in feature binding of a target object rather than to a substitution of an integrated object by the following stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)