Electrophysiological and behavioral indicants of selective attention to multifeature gratings

299

229

Event-related brain potentials (ERPs) were recorded from subjects who attended to pairs of adjacent colored squares that were flashed sequentially to produce a perception of movement. The task was to attend selectively to stimuli in one visual field and to detect slower moving targets that contained the critical value of the attended feature, be it color or movement direction. Attention to location was reflected by a modulation of the early PI and NI components of the ERP,whereas selection of the relevant stimulus feature was associated with later selection negativity components. ERP indices of feature selection were elicited only by stimuli at the attended location and had distinctive scalp distributions for features mediated by "ventral" (color) and "dorsal" (motion) cortical areas. ERP indices of target selection were also contingent on the prior selection of location but initially did not depend on the selection of the relevant feature. These ERP data reveal the timing of sequential, parallel, and contingent stages of visual processing and support early-selection theories of attention that stipulate attentional control over the initial processing of stimulus features.

Section: Selection Hierarchiesmentioning

confidence: 99%

mentioning

confidence: 99%

Selective attention to the color and direction of moving stimuli: Electrophysiological correlates of hierarchical feature selection

Anllo-Vento

Hillyard

1996

299

229

“…The onset of the Ndconj occurred at latencies much shorter than those of the termination of Nd waves associated with frequency and location features. It should also be noted that in the present experiment, unlike that of Previc and Harter (1982), Ndconj waves were extracted from ERPs to nontarget tones that did not cue responses. Thus, Nd-conj waves cannot be related to N2 and P3 components associated with target detection, or to premotor or motor potentials linked to the motor response.…”

Section: Erp Signs Of Auditory Feature Conjunctionmentioning

confidence: 99%

“…Previc and Harter (1982;see also Harter, Aine, & Schroeder, 1982) were the first to use ERP techniques to investigate feature conjunction. Subjects responded to visual targets defined by the conjunction of the orientation and spatial frequency of bar gratings (e.g., small vertical bars).…”

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confidence: 99%

Feature processing during high-rate auditory selective attention

Woods

Alain

1993

Auditory event-related brain potentials (ERPs) and reaction times were analyzed in a selective attention task in which subjects attended to tone pips presented at high rates (interstimulus intervals [ISIs] of 40-200 msec). Subjects responded to infrequent target tones of a specified frequency (250 or 4000 Hz) and location (left or right ear) that were louder than otherwise identical tones presented randomly to the left and right ears. Negative difference (Nd) waves were isolated by subtracting ERPs to tones with no target features from ERPs to the same tones when they shared target location, frequency, or both frequency and location cues. Nd waves began 60-70 msec after tone onset and lasted until 250-350 msec after tone onset, even for tones with single attended cues. The duration ofNd waves exceeded the ISIs between successive tones, implying that several stimuli underwent concurrent analysis. Nd waves associated with frequency processing had scalp distributions different from those associated with location processing, implying that the features were analyzed in distinct cortical areas. Nd waves specific to auditory feature conjunction were isolated. These began at latencies of 110-120 msec, some 30-40 msec after the Nds to single features. The relative timing of the different Nd waves suggests that auditory feature conjunction begins after a brief parallel analysis of individual features but before feature analysis is complete.

“…For example, Previc and Harter (1982) found several time points in the YEP that showed amplitude differences linked to selective attention directed toward the spatial frequency and orientation of a visual stimulus. Hillyard and Miinte (1984) found a number of amplitude differences associated with selective attention to location and color.…”

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confidence: 99%

The temporal distribution of stimulus information in the visual evoked potential

Stanners

Carver

1989

Research in psychophysics (Bloch's law) and perceptual experiments concerned with the integration of successively presented stimuli suggest that the perception of form is a process that occurs over a period of as much as 200-300 msec. Such results prompted the question of whether the visual evoked potential (YEP) might contain information about the distribution over time of perceptual processing. Subjects viewed lines formed from combinations of three lengths and four angles while the EEG was recorded. Analysis of the VEPs indicated that the length and angle of the lines produced temporal distributions of information in the YEP and that the distributions for length and angle were somewhat different. The major difference was that the processing of angle begins earlier and is completed sooner than the processing of length. A conclusion of the experiment was that an alternative or supplement to analyzing VEPs for specific waveform features is to consider the encoding of stimulus information in the YEP as a density or concentration over time.Our principal objective in the present experiment was to investigate the possibility that information from a visual stimulus may be encoded in the visual evoked potential (YEP) in such a way that the information about the stimulus is distributed over a fairly substantial time interval, possibly several hundred milliseconds. Another objective was to investigate whether different physical features of the stimulus-in the present case length and angle of a line-might have different temporal distributions in the YEP.Bloch's law, a well-established finding from visual psychophysics, suggests some approximate intervals for the temporal integration of information in the visual system. Bloch's law states that for some visual tasks, a reciprocity relationship exists between the intensity and duration of a visual stimulus. For example, within a certain time interval, a tradeoff between duration and intensity will yield essentially the same results for perceived brightness. Kahneman and Norman (1964) found the critical (reciprocity) interval for perceived brightness to be approximately 100 msec, which is within the range of findings from numerous other experiments. In the same study, the critical interval for a form perception task (identification of zeros and ones) was also investigated. The critical interval for the form perception task, approximately 250 msec, was substantially longer than that for perceived brightness. In another experiment (Kahneman, Norman, & Kubovy, 1967), the identification task was used in conjunction with dichoptic stimulation. Here the critical interval was at least 300 msec.The authors decided that equal contributions were made to the experiment, so order of authorship was decided by a cointlip. Send for reprints to: Robert F. Stanners, Department of Psychology, Oklahoma State University, Stillwater, OK 74078. 259Another line of research that demonstrates temporal integration of form information in the visual system is exemplified in some experiments by Collins...