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Many factors influence how long it takes to respond to a visual stimulus. The lowest-level factors, such as luminance and contrast, determine how easily different elements of a target can be detected. Higher-level factors are to do with whether these elements constitute a stimulus requiring a response; they include prior probability and urgency. It is(More)
Saccades are the eye movements we make to look at objects. Apart from being astonishingly fast, often lasting little more than 20 milliseconds, they also happen to be the single most frequent movement we make, much commoner than heartbeats: we make two or three saccades every second of our waking lives. Saccades determine what we see, so their importance(More)
In the LATER model, randomness of saccadic latency arises through random variation in the rate of rise of the decision signal. But does it vary independently at different locations? If so, when pairs of targets are presented asynchronously, and the participant makes a saccade to the more salient one, the choice of target should be stochastic. Further, it(More)
Subjects undertook a saccadic gap task, in which the fixation target is extinguished for a period before the appearance of the peripheral stimulus. The majority showed a population of short-latency express saccades in addition to the main, slower, distribution. However, closer analysis showed that nearly all of this bimodality was due to the order in which(More)
For the majority of human smooth pursuit eye movements made to a horizontal ramp target of unpredictable direction, the reciprocal of the latency appears to have a Gaussian distribution of the same general form as for saccades to step targets, but with smaller median. There are more latencies shorter than some 100 msec than would be expected from such a(More)
We compared the effectiveness of central and peripheral targets in a saccadic countermanding task. Stop-signal reaction times (SSRTs) do not differ significantly for central and peripheral stop signals. Further, when central and peripheral stop signals are presented together, SSRTs behave as expected of independent processes in parallel. A linear(More)
Our findings demonstrate a possible behavioral outcome of a visual system with massive retrograde connections between category-sensitive and more primary visual areas [5,12] and suggest a reassessment of theories that eschew top-down conceptual influences on visual selection [13,14]. The present results make it clear that visual perception depends not only(More)
One popular and fruitful approach to understanding what influences the decision of where to look next has been to present targets in a series of trials either to the right or left of a central fixation point and examine sequential effects on saccadic latency. However, there is a problem with this paradigm: Every saccade to a target is necessarily followed(More)