Sander Los
Vrije Universiteit Amsterdam, Cognitive Psychology, Faculty Member
Research Interests:
Research Interests:
Research Interests:
Research Interests: Artificial Intelligence, Modeling, Temporal dynamics, Intelligent Agent, Classical Conditioning, and 10 moreAgent Oriented Software Engineering, Formal Specification, Formal method, Adaptive System, Mathematical Model, Conditioning, Differential equation, Agent Systems, Simulation Model, and Dynamic Properties
Recent studies have shown that switch costs (i.e., slower responding on task-alternation trials than on task-repetition trials) are not observed when on the preceding trial a no-go signal instructed the participant to withhold the... more
Recent studies have shown that switch costs (i.e., slower responding on task-alternation trials than on task-repetition trials) are not observed when on the preceding trial a no-go signal instructed the participant to withhold the response to the target stimulus. This finding suggests that neither task set is inhibited on no-go trials, and that the origin of switch costs is located in the application of the task set to the target stimulus. However, these studies also showed that responding after a no-go trial is substantially slower than after a go trial. This suggests that both task sets are inhibited on no-go trials and that switch costs originate from the preparation of a task set. In two experiments we created conditions that revealed an absence of switch costs in conjunction with relatively fast responding after no-go trials. Together these findings confirm that switch costs originate from the application of the task set.
Research Interests:
Research Interests:
How do participants adapt to temporal variation of preparatory foreperiods? For reaction times, specific sequential effects have been observed. Responses become slower when the foreperiod is shorter on the current than on the previous... more
How do participants adapt to temporal variation of preparatory foreperiods? For reaction times, specific sequential effects have been observed. Responses become slower when the foreperiod is shorter on the current than on the previous trial. If this effect is due to changes in motor activation, it should also be visible in force of responses and in EEG measures of motor preparation, the contingent negative variation (CNV) and the lateralized readiness potential (LRP). These hypotheses were tested in a two-choice reaction task, with targets occurring 500, 1500, or 2500 ms after an acoustic warning signal. The reaction time results showed the expected pattern and were accompanied by similar effects on a fronto-central CNV and the LRP. In contrast, the increase of response force with brief current foreperiods did not depend on previous foreperiods. Thus, EEG measures confirm that sequential effects on RT are at least partially due to changes in motor activation originating from previous trials. Effects found on response force may be related to general response readiness rather than activation of motor-hand areas, which may explain the absence of a sequential effect on force in the current experiment.
Research Interests:
In the study of nonspecific preparation, the response time (RT) to an imperative stimulus is analyzed as a function of the foreperiod (FP), the interval between a warning stimulus and the imperative stimulus. When FP is varied within... more
In the study of nonspecific preparation, the response time (RT) to an imperative stimulus is analyzed as a function of the foreperiod (FP), the interval between a warning stimulus and the imperative stimulus. When FP is varied within blocks of trials, a downward sloping FP—function is usually observed. The slope of this function depends on the distribution of FPs (the more negative the skewness, the steeper the slope) and on intertrial sequences of FP (the longer the FP on the preceding trial, the steeper the slope). Because these determinants are confounded, we examined whether FP—RT functions, observed under three different FP distributions (i.e., uniform, exponential, and peaked) can be predicted, one from the other, by reweighting sequential effects. It turned out that reweighting explained very little variance of the difference between the FP—RT functions, suggesting a dominant role of temporal orienting strategies.
Research Interests:
I examined the relation between two inhibitory processes operating on spatial and temporal representations. In two experiments, participants had to detect a peripheral target that was presented after a variable interval following the... more
I examined the relation between two inhibitory processes operating on spatial and temporal representations. In two experiments, participants had to detect a peripheral target that was presented after a variable interval following the onset of an uninformative peripheral cue. For the shortest cue-target interval, target detection was faster at the cued than at the uncued location, but this effect was reversed for the longer cue-target intervals. This finding has been taken to reflect a buildup of space-related inhibition over time, known asinhibition of return. Also, target detection was slower when the cue-target interval of the preceding trial was longer than that of the current trial than when this was not so. This sequential effect has been taken to reflect an intertrial carryover of time-related inhibition. Crucially, the spatial and temporal effects were additive in both experiments, suggesting a modular organization of the underlying inhibitory processes.
Research Interests: Psychology, Cognitive Science, Psychophysics, Decision Making, Attention, and 15 moreTime Perception, Color Perception, Space perception, Humans, Cues, Orientation, Saccades, Reaction Time, Inhibitory Control, Target Detection, Variable Interval, Short Term Memory, Inhibition of Return, Probability Learning, and Psychomotor Performance
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests: Psychology, Cognitive Psychology, Cognitive Science, Attention, Parallel Processing, and 14 moreStimulus-Response Compatibility, Humans, Cues, Orientation, Reaction Time, Stimuli, Cognitive processes, Experiments, Response-Selection, Adult, Time Factors, Time Course, Intervals, and Psychomotor Performance
Research Interests:
According to the asynchronous discrete coding model of Miller, two manipulations should display underadditive effects on reaction time if they slow down noncontingent stages associated with the processing of two separable dimensions of a... more
According to the asynchronous discrete coding model of Miller, two manipulations should display underadditive effects on reaction time if they slow down noncontingent stages associated with the processing of two separable dimensions of a stimulus. Underadditive effects are also predicted by a dual route model when a task variable is factorially varied with design type (mixed vs blocked). Interpretations of both underadditive effects and their combination were evaluated. Intact and degraded stimuli were presented to 18 young adults either in a single block (mixed) or in separate blocks (blocked). Spatial stimulus-response (S-R) compatibility was manipulated in all conditions. Stimulus degradation and S-R compatibility interacted underadditively, but only in blocked presentations. Both interpretations of underadditive effects were supported. Eye-movement registrations provided additional support for the alternative routes model.