Selective attention in the primate visual system.

A series of single unit PET and behavioural studies is described addressing the functions and neurophysiology of visual attention. Beyond striale cortex, visual information is processed in a network of separate cortical areas, specialized in part for analysis of different visual attributes. Issues arising in such a modular system include the nature of the attentional state in extrastriate cortex, its flexible control by the requirements of current behaviour, and the coordination between areas implied by attention to whole objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective attention and the organization of visual information.

Conducted 4 experiments with 108 volunteers (aged 18-42 yrs) to test object-, discrimination-, and space-based theories of visual attention. In each experiment, Ss were presented with small (     

Splitting visual space with attention.

The present study aimed at showing a spatial compatibility effect (and, by implication, a right–left subdivision of space) solely attributable to the orienting of attention. Five groups of 8 normal Ss were required to give right–left discriminative responses to stimuli presented within one of 6 empty boxes arranged in a horizontal row. Reaction times and errors were recorded. A right–left grouping of the boxes occurred regardless of whether Ss' fixation was kept at the intermediate position (Exp 1) or at one extremity (Exp 2) of the row. In Exps 3 and 4, Ss' attention was not aligned with a fixed position but was moved, through peripheral cues, from trial to trial and positioned between different pairs of adjacent boxes. Results showed that the display was again subdivided into 2 regions and that the reference point for the right–left subdivision was the focus of attention. In Exp 5, eye position was instrumentally monitored, and Ss' attention was directed by central cues. The results confirmed that the focusing of attention leads to a right–left partitioning of space. Directing attention to a position in space brings about a right–left perceptual organization that predominates over that provided by the other egocentric reference axes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interaction of hypertension and age in visual selective attention performance.

Previous research suggests that some aspects of cognitive performance decline as a joint function of age and hypertension. In this experiment, 51 unmedicated individuals with mild essential hypertension and 48 normative individuals, 18–78 yrs of age, performed a visual search task. The estimated time required to identify a display character and shift attention between display positions increased with age. This attention shift time did not differ significantly between hypertensive and normotensive participants, but regression analyses indicated some mediation of the age effect by blood pressure. For individuals less than 60 yrs of age, the error rate was greater for hypertensive than for normotensive participants. Although the present design could detect effects of only moderate to large size, the results suggest that effects of hypertension may be more evident in a relatively general measure of performance (mean error rate) than in the speed of shifting visual attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of display resolution on visual performance

Comparative sequence analysis of small subunit rRNA is currently one of the most important methods for the elucidation of bacterial phylogeny as well as bacterial identification. Phylogenetic investigations targeting alternative phylogenetic markers such as large subunit rRNA, elongation factors, and ATPases have shown that 16S rRNA-based trees reflect the history of the corresponding organisms globally. However, in comparison with three to four billion years of evolution the phylogenetic information content of these markers is limited. Consequently, the limited resolution power of the marker molecules allows only a spot check of the evolutionary history of microorganisms. This is often indicated by locally different topologies of trees based on different markers, data sets or the application of different treeing approaches. Sequence peculiarities as well as methods and parameters for data analysis were studied with respect to their effects on the results of phylogenetic investigations. It is shown that only careful data analysis starting with a proper alignment, followed by the analysis of positional variability, rates and character of change, testing various data selections, applying alternative treeing methods and, finally, performing confidence tests, allows reasonable utilization of the limited phylogenetic information.     

Search images: Selective attention to specific visual features of prey.

In 3 experiments, pigeons (Columba livia) searched a digitized image of a gravel patch on a computer monitor for cryptic grains. Experiment 1 demonstrated that the bird's ability to detect a type of grain improved over successive encounters, and detection of alternative targets was attenuated when a search image was active. Experiment 2 demonstrated search-image effects independently for the 2 grains. Perception was biased to detect wheat grains after wheat encounters and was biased to detect bean grains after bean encounters. Experiment 3 demonstrated that when a search image was activated, selective attention was heightened to the visual features of the grain used to discriminate it from the multicolor gravel background. These results provide strong support for the view that search images are selective attention to specific visual features of cryptic prey. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tracking performance on a visual display apparently vibrating at one to ten Hertz.

20 20-34 yr. old males performed compensatory 2-dimensional tracking on a visual display. This was viewed through a periscope, the lower mirror of which was oscillated about an axis so as to impose apparent vertical vibration on the display. The vibration frequency range 1-10 Hz. was explored, at (double) amplitudes of 2 and 4–. The decrement due to apparent vibration was frequency dependent, being greatest at those frequencies (3-5 Hz.) where a changeover in viewing technique was taking place. Over this range, progressively, reflexive eye pursuit is abolished and a virtual image at the limit of vibration excursion becomes usable. Data from eye movement studies on an additional group of 6 Ss corroborate this. (27 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective and divided attention in a Stroop task.

Three experiments employed a modified version of the Stroop Color-Word Test to document some conditions under which attention may be differentially deployed. Ss were 66 undergraduates. Within limits, Ss chose either to selectively attend to a single stimulus or to distribute processing resources over several stimuli. Thus, attentional strategies may be actively chosen to suit prevailing conditions. Once established, these different modes of attending were themselves differentially open to strategic modulation. (French abstract) (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective attention in schizophrenia.

Administered 8 dichotic shadowing tasks to 4 groups of patients, (delusional and nondelusional schizophrenics, nonschizophrenic psychiatric patients, and nonpsychiatric patients). The distraction used in the tasks was varied to determine which, if any, of the mechanisms involved in selective attention may be dysfunctional in schizophrenics. It was found that the topic of the distraction affected the performance of delusional schizophrenics differently than it affected the performance of the other groups. The loudness of the distraction affected all groups identically. Results suggest that attentional dysfunction in schizophrenia may be the product not of a breakdown of any of the mechanisms of selective attention but rather of an unusual manner of allocation attention. Delusional schizophrenics evidently differ from nonschizophrenics in the nature of the stimuli to which they attend and not in the actual ability to attend. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory and visual capture during focused visual attention.

It is well known that auditory and visual onsets presented at a particular location can capture a person’s visual attention. However, the question of whether such attentional capture disappears when attention is focused endogenously beforehand has not yet been answered. Moreover, previous studies have not differentiated between capture by onsets presented at a nontarget (invalid) location and possible performance benefits occurring when the target location is (validly) cued. In this study, the authors modulated the degree of attentional focus by presenting endogenous cues with varying reliability and by displaying placeholders indicating the precise areas where the target stimuli could occur. By using not only valid and invalid exogenous cues but also neutral cues that provide temporal but no spatial information, they found performance benefits as well as costs when attention is not strongly focused. The benefits disappear when the attentional focus is increased. These results indicate that there is bottom-up capture of visual attention by irrelevant auditory and visual stimuli that cannot be suppressed by top-down attentional control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial attention to arrays of multidimensional objects.

Encoding briefly displayed arrays of multidimensional objects appears to require selective attention, but this hypothesis is challenged by M. J. Nissen's (1985) finding that properties of an object are reported independently. Selective attention to some objects but not others should produce positive dependence. Theoretical analysis shows that deviations from independence would have been difficult to observe in Nissen's data because of high guessing rates and small sample sizes. Four new experiments showing strong positive dependence in property reports are described. Deviations from independence were highly significant for most Ss. Quantitative modeling shows that selective attention to subsets of objects would produce about the amount of dependence obtained. Rather than challenging attention theories, the amount of dependence in encoding multidimensional objects is consistent with selective attention to either objects or locations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective attention and visual search: Revision of an allocation model and application to age differences.

Examined in 3 experiments a revised version of the Eriksen and Yeh (C. W. Eriksen and Y.-Y. Yeh, 1985) model of attentional allocation during visual search. Results confirmed the assumption of the model that performance represents a weighted combination of focused- and distributed-attention trials, although Ss relied on focused attention more than was predicted. Consistent with the model, predictions on the basis of the assumption of a terminating search fit the data better than predictions on the basis of an exhaustive search. The effects of varying cue validity favored an interpretation of focused attention in terms of a processing gradient rather than a zoom lens. Although the allocation of attention across trials was similar for young and older adults, there was an age-related increase in the time required to allocate attention within individual trials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Semantic contextual cuing and visual attention.

Since M. M. Chun and Y. Jiang's (1998) original study, a large body of research based on the contextual cuing paradigm has shown that the visuocognitive system is capable of capturing certain regularities in the environment in an implicit way. The present study investigated whether regularities based on the semantic category membership of the context can be learned implicitly and whether that learning depends on attention. The contextual cuing paradigm was used with lexical displays in which the semantic category of the contextual words either did or did not predict the target location. Experiments 1 and 2 revealed that implicit contextual cuing effects can be extended to semantic category regularities. Experiments 3 and 4 indicated an implicit contextual cuing effect when the predictive context appeared in an attended color but not when the predictive context appeared in an ignored color. However, when the previously ignored context suddenly became attended, it immediately facilitated performance. In contrast, when the previously attended context suddenly became ignored, no benefit was observed. Results suggest that the expression of implicit semantic knowledge depends on attention but that latent learning can nevertheless take place outside the attentional field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A theory of visual attention.

A unified theory of visual recognition and attentional selection is developed by integrating the biased-choice model for single-stimulus recognition (R. D. Luce, 1963; R. N. Shepard, 1957) with a choice model for selection from multielement displays (C. Bundesen et al; see record 1985-05669-001) in a race model framework. Mathematically, the theory is tractable, and it specifies the computations necessary for selection. The theory is applied to extant findings from a broad range of experimental paradigms. The findings include effects of object integrality in selective report, number and spatial position of targets in divided-attention paradigms, selection criterion and number of distracters in focused-attention paradigms, delay of selection cue in partial report, and consistent practice in search. On the whole, the quantitative fits are encouraging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Decision quality as a measure of visual display effectiveness.

A new gaming technique was employed in an attempt to evaluate more accurately the effectiveness of visual displays. 18 male university students acted as traffic managers for a hypothetical trucking concern. Trucking information was presented in map-plus-overlay displays, and Ss manipulated trucks, drivers, and loads within the framework of the economic rules governing the trucking operation. A computer program was written which determined the profit in dollars of each S's performance. 3 independent variables—use of color, fact density, and compression (ratio of symbols to facts)—were used in this repeated measures design. Analysis of variance indicated that profit was a positive function of increasing fact density (p     

Comparison of two visual display presentations.

The applicability of the results of dial legibility studies based on slide presentations to legibility of actual dials was tested experimentally by comparison of time and error measures for reading actual dials, and reading slide projections of the dials. There was a slight but insignificant advantage in favor of panelmounted slides over projection of pictures of the slides. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Allocating visual attention: Tests of a two-process model.

Observers require less time to identify a visual target when its location is cued in advance than when it is not cued, and the magnitude of the improvement depends on the validity of the cue. According to J. Jonides's (1983) 2-process model, there exist 2 possible modes of attentional readiness: a focused-attention mode and a diffuse-attention mode. Observers are assumed to enter the focused-attention mode on a proportion of trials that matches the validity of the cue and to enter the diffuse-attention mode on the remaining trials. The present experiment tested and rejected the response time mixture prediction of the 2-process model. An instance of the class of 1-process models in which perceptual objects are sampled in parallel according to the validity of the cue was evaluated. A stochastic simulation of the model yielded results that paralleled those of the experiment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and shifts of visual spatial attention.

Three experiments examined adult age differences in the efficiency of endogenous (voluntary) and exogenous (involuntary) attention shifts. Younger and older Ss performed a spatial cuing task in which abruptly onset peripheral cues (Exp 1) or central, symbolic cues (Exps 2 and 3) were presented before a target stimulus at intervals ranging from 50 to 250 msec. With peripheral cues, the magnitude of cuing effects was at least as great for older as for younger adults and followed a similar time course. Similar results were obtained with symbolic cues, although cuing effects for older adults varied with cue difficulty. The results suggest that cue encoding may decline with advancing age but that the efficiency of the shift process is preserved. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective attention in animal discrimination learning.

2 classes of experiment on the role of attention in discrimination learning are reviewed: (a) Investigations of the effect of attention on the amount learned about different cues have been interpreted as disproving noncontinuity theory (according to which animals attend to only 1 cue at a time). The fact that animals learn something about a 2nd cue, however, does not prove that attention has no effect on learning, and more recent evidence shows that it does. (b) If animals do not automatically attend to all cues, part of what they must learn in order to solve a discrimination problem is to attend to the relevant cue. Experiments on the acquired distinctiveness of cues, transfer along a continuum, and reversal learning provide evidence for the importance of such classificatory learning. (155 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selective attention and clinical depression: Performance on a deployment-of-attention task.

Clinically depressed and nondepressed individuals completed a deployment-of-attention task developed by I. H. Gotlib, A. L. McLachlan, and A. N. Katz (1988). Results indicated that the clinically depressed individuals perform the task in an unbiased fashion, attending equally to positive-, negative-, and neutral-content stimuli. In contrast, the nondepressed individuals demonstrated a "protective" bias against the perception of negative stimuli by avoiding such material in favor of positive or neutral stimuli. Overall, the results of this study suggest that clinically depressed individuals do not show an attentional bias toward negative information, but rather, fail to demonstrate the positive or protective bias that is evident in nondepressed individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)