Visual offsets facilitate saccadic latency: Does predisengagement of visuospatial attention mediate this gap effect?

Saccadic reaction time (RT) is reduced when a fixation stimulus is extinguished 200 msec before a target appears. An attentional predisengagement theory (APT) may explain this gap effect: When covert attention is engaged (e.g., on fixation), the saccadic system is inhibited and RT is delayed; when the attended stimulus is extinguished, attention is disengaged, the inhibition is removed, and RT is facilitated. In 3 experiments covert attention was endogenously or exogenously cued to an object on the vertical meridian. Onset of a saccadic target on the horizontal meridian could be preceded by the offset of an attended or unattended object. Contrary to APT, RTs were identical after attended and unattended offsets. Results suggest that the gap effect has 2 components, and covert visual attention plays no role. One component is motor system preparation; the other is a fixation offset effect specific to the oculomotor system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The retinotopy of visual spatial attention

We used high-field (3T) functional magnetic resonance imaging (fMRI) to label cortical activity due to visual spatial attention, relative to flattened cortical maps of the retinotopy and visual areas from the same human subjects. In the main task, the visual stimulus remained constant, but covert visual spatial attention was varied in both location and load. In each of the extrastriate retinotopic areas, we found MR increases at the representations of the attended target. Similar but smaller increases were found in V1. Decreased MR levels were found in the same cortical locations when attention was directed at retinotopically different locations. In and surrounding area MT+, MR increases were lateralized but not otherwise retinotopic. At the representation of eccentricities central to that of the attended targets, prominent MR decreases occurred during spatial attention.     

Spatial maps of directed visual attention.

Previous studies have shown that simple reaction times (RTs) to a visual target are facilitated when the target occurs at a location expected by an observer and are slowed when the target occurs at the mirror-symmetric location contralateral to the expectancy. The present 7 experiments, with 8 observers, examined the spatial extent of this attention effect by inducing Ss to expect the target at 1 location and introducing occasional probe flashes at other locations throughout the visual field. RTs to these probes were equivalent to those obtained at the expected location so long as the probe was in the same hemifield as the S's expectancy. Conversely, RTs to probes in the hemifield opposite the expectancy generated uniformly slower response times. These results were obtained when the expected location varied in eccentricity from 2° to 16° along the horizontal meridian. In addition, when the expected and unexpected locations were within the same hemifield, no expectancy effects were observed. Under these conditions, the frequently used metaphor that directed visual attention operates like a spatially restricted "beam" appears inaccurate. Implications for current views of directed attention are considered. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of inter- and intramodal selective attention to non-spatial visual stimuli: an event-related potential analysis

Event-related potentials (ERPs) were recorded to trains of rapidly presented auditory and visual stimuli. ERPs in conditions in which subjects attended to different features of visual stimuli were compared with ERPs to the same type of stimuli when subjects attended to different features of auditory stimuli. This design permitted us to study effects of variations in both intramodal and intermodal visual attention on the timing and topography of ERP components in the same experiment. There were no indications that exogenous N110, P140 and N180 components to line gratings of high and low spatial frequencies were modulated by either intra- or intermodal forms of attention. Furthermore, intramodal and intermodal attention effects on ERPs showed similar topographical distributions. These combined findings suggest that the same neural generators in extrastriate occipital areas are involved in both forms of attention. Visual ERPs elicited in the condition in which subjects were engaged in auditory selective attention showed a large positive displacement at the occipital scalp sites relative to ERPs to attended and unattended stimuli in the visual condition. The early onset of this positivity might be associated with a highly confident and early rejection of the irrelevant visual stimuli, when these stimuli are presented among auditory stimuli. In addition, the later onset of selection potentials in the intramodal condition suggests that a more precise stimulus selection is needed when features of visual stimuli are rejected among other features of the same stimulus pattern, than when visual stimuli are rejected among stimuli of another modality.     

Sustained visual-spatial attention produces costs and benefits in response time and evoked neural activity

This study investigated the simple reaction time (RT) and event-related potential (ERP) correlates of biasing attention towards a location in the visual field. RTs and ERPs were recorded to stimuli flashed randomly and with equal probability to the left and right visual hemifields in the three blocked, covert attention conditions: (i) attention divided equally to left and right hemifield locations; (ii) attention biased towards the left location; or (iii) attention biased towards the right location. Attention was biased towards left or right by instructions to the subjects, and responses were required to all stimuli. Relative to the divided attention condition, RTs were significantly faster for targets occurring where more attention was allocated (benefits), and slower to targets where less attention was allocated (costs). The early P1 (100-140 msec) component over the lateral occipital scalp regions showed attentional benefits. There were no amplitude modulations of the occipital N1 (125-180 msec) component with attention. Between 200 and 500 msec latency, a late positive deflection (LPD) showed both attentional costs and benefits. The behavioral findings show that when sufficiently induced to bias attention, human observers demonstrate RT benefits as well as costs. The corresponding P1 benefits suggest that the RT benefits of spatial attention may arise as the result of modulations of visual information processing in the extrastriate visual cortex.     

Effects of altering brain cholinergic activity on covert orienting of attention: comparison of monkey and human performance

Experiments were conducted to elucidate the role of the cholinergic neurotransmitter system in arousal and the orienting of attention to peripheral targets. Rhesus monkeys and humans fixated a visual stimulus and responded to the onset of visual targets presented randomly in two visual field locations. The target was preceded by a valid cue (cue and target at the same location), an invalid cue (cue and target to opposite locations), a double cue (cues to both spatial locations, target to one), or, the cue was omitted (no-cue, target to either location). Reaction times (RTs) to the onset of the target were recorded. For monkeys, systemic injections of nicotine (0.003-0.012 mg/kg) or atropine (0.001-0.01 mg/kg), but not saline control injections, reduced mean RTs for all trials, indicating general behavioral stimulation. In addition, nicotine significantly reduced RTs for invalid trials but had little additional effect on those for valid, double, or no-cue trials. Virtually identical effects were observed for human chronic tobacco smokers in performing the same task following cigarette smoking. Injections of atropine in monkeys had no effect on RTs for valid or invalid trials but significantly slowed RTs in double-cue trials that did not require the orienting of attention. These results suggest that in both species, the nicotinic cholinergic system may play a role in automatic sensory orienting. In addition, the muscarinic system may play a role in alerting to visual stimuli in monkeys.     

Spatial factors in visual attention: A reply to Crassini.

Notes that distances between stimuli and compactness of stimulus subsets are pervasive determiners of discrimination and classification performance. Contrary to B. Crassini (see record 1986-26308-001), these factors are sufficient to account for the major patterns in the chronometric data of the present authors (see PA, Vols 61:259 and 71:3057). Other factors, such as the dichotomous one distinguishing what Crassini terms unitary and nonunitary subsets, may exert some additional influence. But a convincing demonstration would require formulation of a quantitative model capable of being pitted against the present authors' distance-based model within the context of their entire body of data. (22 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Stimulus-response compatibility with relevant and irrelevant stimulus dimensions that do and do not overlap with the response.

Five experiments were conducted using 4- and 6-choice stimulus–response compatibility tasks with graphic and alphabetic stimuli, and keypress and verbal responses. A comparison of performance with compatible, incompatible, and neutral conditions shows that when a stimulus set is perceptually, conceptually, or structurally similar to a response set, (a) mean reaction times (RTs) are faster when individual stimuli and responses match than when they do not match, (b) this is true whether the stimulus and response sets are similar on relevant or irrelevant dimensions, (c) this "compatibility effect" is greater when the dimensions are relevant than when they are irrelevant, and (d) whether the dimensions are relevant or irrelevant, the faster RTs are due to a facilitative process and the slower RTs to an interfering process. These results are accounted for by the dimensional overlap model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional MRI reveals spatially specific attentional modulation in human primary visual cortex

Selective visual attention can strongly influence perceptual processing, even for apparently low-level visual stimuli. Although it is largely accepted that attention modulates neural activity in extrastriate visual cortex, the extent to which attention operates in the first cortical stage, striate visual cortex (area V1), remains controversial. Here, functional MRI was used at high field strength (3 T) to study humans during attentionally demanding visual discriminations. Similar, robust attentional modulations were observed in both striate and extrastriate cortical areas. Functional mapping of cortical retinotopy demonstrates that attentional modulations were spatially specific, enhancing responses to attended stimuli and suppressing responses when attention was directed elsewhere. The spatial pattern of modulation reveals a complex attentional window that is consistent with object-based attention but is inconsistent with a simple attentional spotlight. These data suggest that neural processing in V1 is not governed simply by sensory stimulation, but, like extrastriate regions, V1 can be strongly and specifically influenced by attention.     

The effect of fear and anger on selective attention.

This experiment examined the effects of two discrete negative emotions, fear and anger, on selective attention. A within-subjects design was used, and all participants (N = 98) experienced the control, anger, and fear conditions. During each condition, participants viewed a film clip eliciting the target emotion and subsequently completed a flanker task and emotion report. Selective attention costs were assessed by comparing reaction times (RTs) on congruent (baseline) trials with RTs on incongruent trials. There was a significant interaction between emotion condition (control, anger, fear) and flanker type (congruent, incongruent). Contrasts further revealed a significant interaction between emotion and flanker type when comparing RTs in the control and fear conditions, and a marginally significant interaction when comparing RTs in the control and anger conditions. This indicates that selective attention costs were significantly lower in the fear compared to the control condition and were marginally lower in the anger compared with the control condition. Further analysis of participants reporting heightened anger in the anger condition revealed significantly lower selective attention costs during anger compared to a control state. These findings support the general prediction that high arousal negative emotional states inhibit processing of nontarget information and enhance selective attention. This study is the first to show an enhancing effect of anger on selective attention. It also offers convergent evidence to studies that have previously shown an influence of fear on attentional focus using the global-local paradigm. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Imagery-perception interaction depends on the shape of the image: A reply to Farah (1989).

M. J. Farah (see record 1989-31784-001) reported that point threshold stimuli are detected better if they appear at spatial locations in the visual field that are covered by an image. By replicating her experiment with 3 instead of the original 2 images, it was found that the effect depends on the shape of the mentally projected image. A 2nd experiment with 9 different shapes revealed that the effect is modulated by the compactness and the size of the image; it is enhanced with increasing compactness and attenuated with increasing size. These findings do not unequivocally support the idea that imagery and perception interact because both processes share the same representational medium. Rather, they suggest that imagery can cause a figure–ground segregation in the visual field and that the shape of the figure may determine the amount of attention that is allocated to different sections in the visual field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention During Adaptation Weakens Negative Afterimages.

The effect of attention during adaptation on subsequent negative afterimages was examined. One of 2 overlapped outline figures was attended during a 7-10-s adaptation period. When the figures were readily perceptually segregated (on the basis of color or motion), the subsequent afterimages were initially weaker for the previously attended figure. This effect was confirmed by demonstrations that the onset of a single afterimage was delayed when an afterimage inducer was attended during adaptation compared with when a central digit stream or an overlapped (brightness-balanced) figure that did not generate an afterimage was attended. The attention effect was further confirmed using a criterion-independent (dot-integration) paradigm. The fact that selective attention during adaptation weakened or delayed afterimages suggests that attention primarily facilitates the adaptation of polarity-independent processes that modulate the visibility of afterimages rather than facilitating the adaptation of polarity-selective processes that mediate the formation of afterimages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional effects on Necker cube adaptation.

If subjects adapt to an unambiguous version of a Necker cube, a subsequent ambiguous cube tends to be seen in the opposing perspective. The present experiment shows that this adaptation effect depends on whether the adapting cube is attended. During the adaptation phase, 12 Ss saw 2 superimposed cubes of opposite perspective and different sizes and colors centered on fixation. Ss detected color changes in line segments that defined either the small or large cube. The perception of the subsequent ambiguous cube depended on which of the adapting cubes was task relevant. This attentional effect showed a strong asymmetry. When Ss attended to the small adapting cube, an aftereffect appropriate to the perspective of the cube was found, but when the large adapting cube was attended, no aftereffect was present. This asymmetry may relate to constraints on the spatial distribution of attention. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychological aspects of smoker-nonsmoker interaction: Implications for public policy.

Legislated restriction of public smoking has become increasingly common on both the state and federal level over the past 2 decades. The resulting controversy has generally focused on the physiological effects of second-hand smoke while ignoring psychological aspects of smoker–nonsmoker interaction. This article reviews the psychological literature related to this issue and concludes (1) that legislated separation of these groups is necessary and (2) that this can be accomplished successfully only when those creating no-smoking and smoking-permitted areas pay close attention to environmental cues attended to by the users of those areas. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On hearing what you listen for: The effects of attention and expectancy.

Listening differs from hearing just as looking differs from seeing. Listening and looking imply an active, conscious attention to sound or sight, often to particular stimuli. Whereas looking is made obvious by eye or head movement, listening usually involves a more subtle, internal setting. Such selective listening is frequently cited with respect to the so-called cocktail-party effect, the ability to pick out and attend to one of many talkers. In this article, the author does not deal directly with the cocktail-party effect, but presents data to show how attention and expectation affect the processing of simple sounds. These are first steps toward an analytic understanding of the psychophysical bases of the selective attention to one sound among many. Selective listening benefits the detection of sounds in an attended spectral region, but has little effect on the detection of sounds coming from an attended spatial region or in an attended temporal pattern. As to its effect on auditory discrimination and recognition, we know only that selective listening speeds the discrimination of sounds from an attended direction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial attention effects in macaque area V4

Focal visual attention typically produces enhanced perceptual processing at the psychological level and relatively stronger neural responses at the physiological level. A longstanding mechanistic question is whether these attentional effects pertain specifically to the attended (target) object or to the region of space it occupies. We show here that attentional response enhancement in macaque area V4 extends to behaviorally irrelevant objects in the vicinity of the target object, indicating that focal attention has a strong spatial component at the physiological level. In addition, we find that spatial attention effects typically show a striking directional asymmetry. The direction of the asymmetry varies between cells, so that some cells respond best when attention is directed to the left of the stimulus, some when attention is directed to the right, etc. Thus, attention involves not only enhanced responses to behavioral targets but also a complex modulation of responses to other stimuli in the surrounding visual space.     

The gradient of spatial auditory attention in free field: an event-related potential study

Young adult subjects attended selectively to brief noise bursts delivered in free field via a horizontal array of seven loudspeakers spaced apart by 9 degrees of angle. Frequent "standard" stimuli (90%) and infrequent "target/deviant" stimuli (10%) of increased bandwidth were delivered at a fast rate in a random sequence equiprobably from each speaker. In separate runs, the subjects' task was to selectively attend to the leftmost, center, or rightmost speaker and to press a button to the infrequent "target" stimuli occurring at the designated spatial location. Behavioral detection rates and concurrently recorded event-related potentials (ERPs) indicated that auditory attention was deployed as a finely tuned gradient around the attended sound source, thus providing support for gradient models of auditory spatial attention. Furthermore, the ERP data suggested that the spatial focusing of attention was achieved in two distinct stages, with an early more broadly tuned filtering of inputs occurring over the first 80-200 msec after stimulus onset, followed by a more narrowly focused selection of attended-location deviants that began at around 250 msec and closely resembled the behavioral gradient of target detections.     

Activation of lexical codes for simultaneously presented words: Modulation by attention and pathway strength.

Horizontal and vertical strings were presented in a "crosswords" format within left or right visual fields. Distractor strings were varied to examine the extent to which prelexical, orthographic–phonological, and semantic codes are activated for words not focally attended. The results supported 2 predictions of the pathway strength model of attentional modulation (J. D. Cohen, K. Dunbar, & J. L. McClelland, 1990). First, distractor influences were greater when participants attended to the weaker (i.e., vertical) item and ignored the stronger (i.e., horizontal) string, than vice versa. Second, distractors similar to the target facilitated, whereas dissimilar distractors interfered with, pronunciation responses. It is concluded that spatial attention can modulate word recognition processes, and that some interesting questions emerge when one abandons the assumptions of serial, noninteractive word recognition processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of selective attention in the perception of multiple-element stimulus arrays.

To access the role of attention in visual processing, we have recorded single-unit activity from area V4 of visual cortex in macaque monkeys, and the results of these experiments provide a clear demonstration of the relationship between inter-stimulus competition and attention. Specifically, attended stimuli elicit larger responses than ignored stimuli, and these attention effects are increased when: a) the total number of distracting stimuli is increased; b) both attended and ignored stimuli are located inside the neuron's receptive field; and c) the attended and ignored stimuli are presented simultaneously rather than sequentially. We have also examined the role of inter-stimulus competition in human subjects by recording event-related potentials (ERPs), which are electrophysiological responses that can be recorded noninvasively from the scalp. In these experiments, we have found that the attention-sensitive N2pc wave is present when subjects focus attention onto target stimuli when they are surrounded by competing distractor stimuli, but is absent when the competition is eliminated (e.g. by removing the distractors). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is there feature-based attentional selection in visual search?

A new paradigm combines attentional cuing and rapid serial visual presentation to disentangle the effects of perceptual filtering and location selection. Observers search successive, superimposed arrays, in which feature values are alternated for a target numeral among letters. Two dimensions, size (small, large) and color (red, green) are tested. Selective attention to feature values is jointly manipulated by instructions, presentation probabilities, and payoffs. In Experiment 1, the attended feature provides temporal, not spatial, information; observers show no attentional costs or benefits in response accuracy. In Experiment 2, the attended feature indicates a unique location; observers show consistent attentional costs and benefits. Selective attention to a particular size or color does not cause perceptual exclusion or admission of items containing that feature; it acts by guiding search processes to spatial locations that contain the to-be-attended feature. (PsycINFO Database Record (c) 2010 APA, all rights reserved)