Stimulus discriminability in visual search

Verghese, Preeti; Nakayama, Ken

doi:10.1016/0042-6989(94)90289-5

Cited by 130 publications

(98 citation statements)

References 30 publications

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“…Psychophysical observations that visual discrimination improves with increasing stimulus duration support the view that sensory evidence is accumulated over time (Bergen and Julesz, 1983;Saarinen, 1988;Shibuya and Bundesen, 1988;Britten et al, 1992;Verghese and Nakayama, 1994;Ratcliff and Rouder, 2000;Bodeló n et al, 2007) (but see Kiani et al, 2008). Neurophysiological studies of sensory-motor neurons in decision tasks corroborate this interpretation.…”

Section: Introductionsupporting

confidence: 69%

Beneficial Effects of the NMDA Antagonist Ketamine on Decision Processes in Visual Search

Shen¹,

Kalwarowsky²,

Clarence³

et al. 2010

Journal of Neuroscience

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The ability of sensory-motor circuits to integrate sensory evidence over time is thought to underlie the process of decision-making in perceptual discrimination. Recent work has suggested that the NMDA receptor contributes to mediating neural activity integration. To test this hypothesis, we trained three female rhesus monkeys (Macaca mulatta) to perform a visual search task, in which they had to make a saccadic eye movement to the location of a target stimulus presented among distracter stimuli of lower luminance. We manipulated NMDA-receptor function by administering an intramuscular injection of the noncompetitive NMDA antagonist ketamine and assessed visual search performance before and after manipulation. Ketamine was found to lengthen response latency in a dose-dependent fashion. Surprisingly, it was also observed that response accuracy was significantly improved when lower doses were administered. These findings suggest that NMDA receptors play a crucial role in the process of decision-making in perceptual discrimination. They also further support the idea that multiple neural representations compete with one another through mutual inhibition, which may explain the speedaccuracy trade-off rule that shapes discrimination behavior: lengthening integration time helps resolve small differences between choice alternatives, thereby improving accuracy.

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Section: Introductionsupporting

confidence: 69%

Beneficial Effects of the NMDA Antagonist Ketamine on Decision Processes in Visual Search

Shen¹,

Kalwarowsky²,

Clarence³

et al. 2010

Journal of Neuroscience

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“…More guidance yields shallower slopes (Wolfe, 1994;Wolfe et al, 1989;Wolfe & Gancarz, 1996). Other theories lead to similar conclusions by rather different routes (e.g., similarity theory, Duncan & Humphreys, 1989; or signal detection approaches, Chun & Wolfe, 1996;Eckstein, Thomas, Palmer, & Shimozaki, 1996;Hübner, 1993;Palmer, 1994;Swensson & Judy, 1981;Verghese & Nakayama, 1994). If tasks differ only in the strength of the target signal, and if targetpresent slopes reflect that strength, then all searches with the same target-present slope should be the same.…”

Section: Differences Between Types Of Search Taskmentioning

confidence: 99%

What Can 1 Million Trials Tell Us About Visual Search?

1998

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Abstract-In a typical visual search experiment, observers look through a set of items for a designated target that may or may not be present. Reaction time (RT) is measured as a function of the number of items in the displayThe visual search paradigm has been a pillar of research in visual attention for more than 20 years. In a typical visual search experiment, observers are presented with a display containing a number of items. On each trial, the observers must determine if a specific target item is or is not present among the distractor items. The number of items ( set size ) varies from trial to trial. Experimenters measure the reaction time (RT), the amount of time that is required to make a "target-present" or "targetabsent" response. They also note the accuracy of that response. Changes in accuracy and RT as a function of set size constitute the preferred measures of search performance (for a review, see Wolfe, in press).The search paradigm is valuable because performance on these tasks varies in a systematic way with the nature of the search stimuli. For some tasks, performance does not depend on set size. For example, in a search for a red spot among green spots, the number of green spots is irrelevant. Accuracy will be high and RT fast for all set sizes. The slope of the RT × Set Size function will be near zero. The independence of RT and set size is consistent with parallel processing of all items. For other tasks, RT is a roughly linear function of set size. For example, in a search for an S among mirror-reversed S s, RTs will increase at a rate of approximately 20 to 30 ms/item for target-present trials and 40 to 60 ms/item for target-absent trials. The linear increase in RT and the 2:1 ratio between target-absent and target-present slopes is characteristic of a serial, self-terminating search, though it is also consistent with various limited-capacity (Townsend, 1971(Townsend, , 1990) and unlimited-capacity (Palmer & McLean, 1995) parallel search processes.In part because of results of this sort, searches have been divided into parallel searches, in which all items can be processed in a single step, and serial searches, in which attention is deployed from item to item until the target is found. Treisman and Gelade (1980) proposed that searches for basic features like color, motion, and orientation are parallel, whereas other searches, like those for S s among mirrorreversed S s, are serial. Further, they argued that conjunction searches fall into the serial category. These are searches in which the target is defined by two or more basic features. For example, the target might be a small blue item among big blue and small yellow items. Subsequent 0.research has shown that many conjunction searches are more efficient than would be predicted by a strictly serial search (e.g., Cohen, 1993;Cohen & Ivry, 1991;Dehaene, 1989;Egeth, Virzi, & Garbart, 1984;McLeod, Driver, & Crisp, 1988;McLeod, Driver, Dienes, & Crisp, 1991;Nakayama & Silverman, 1986;Sagi, 1988;Theeuwes & Kooi, 1994;Treisman & Sato, 1990;von d...

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“…Although search for an image feature may lead to flat search slopes when the strength of that feature present in the target is much larger than the strength of that feature present in the distractors, pop-out is not necessarily an all-or-nothing affair. Pop-out may occur above a certain threshold of target-distractor difference along the feature dimension that defines the target as a target (Dosher, 1998;Nakayama & Joseph, 1998;Verghese & Nakayama, 1994). Below this threshold, however, search slopes may not be flat.…”

Section: Experiments 6 the Degree Of Pop-out Due To Curvature Discontimentioning

confidence: 99%

Curvature discontinuities are cues for rapid shape analysis

Kristjánsson

Tse

2001

Perception & Psychophysics

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Using the visual search method, we show that stimuli that contain curvature discontinuities (i.e., points where the second derivative along an image contour is not defined) are easily found among stimuli containing only smooth changes in curvature. Curved stimuli that lack curvature discontinuities, however, are difficult to find among distractors that have them. These results suggest that the visual system detects and analyzes abrupt changes in curvature in the image quickly to extract vital information about the 3-D structure of the visual environment

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Stimulus discriminability in visual search

Cited by 130 publications

References 30 publications

Beneficial Effects of the NMDA Antagonist Ketamine on Decision Processes in Visual Search

Beneficial Effects of the NMDA Antagonist Ketamine on Decision Processes in Visual Search

What Can 1 Million Trials Tell Us About Visual Search?

Curvature discontinuities are cues for rapid shape analysis

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