References of "Gorea, Andrei"
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See detailIntrospective duration estimation of reactive and proactive motor responses.
Gorea, Andrei; Mamassian, Pascal; Cardoso-Leite, Pedro UL

in Acta psychologica (2010), 134(2), 142-53

The metajudgment of motor responses refers to our ability to evaluate the accuracy of our own actions. Can humans metajudge the duration of their Reaction Times (RTs) to a light-flash and the accuracy of ... [more ▼]

The metajudgment of motor responses refers to our ability to evaluate the accuracy of our own actions. Can humans metajudge the duration of their Reaction Times (RTs) to a light-flash and the accuracy of their reproduction of a reference time interval bounded by two light flashes (Anticipatory Response Time, ART)? A series of four distinct experiments shows that RT_Meta and ART_Metajudgments are possible but with accuracies about x2.4 and x3 poorer than the corresponding RT and ART ones. In order to reveal the origin of this drop in performance, we ask whether a visual feedback synchronous with subjects' key-presses could improve performance. We show that overall the presence of a visual feedback does not significantly improve metajudgment accuracy although such a trend is noticeable in ART_Meta. We then compare these performances with the passive perceptual estimation of the played back (Pb) RT and ART time intervals when bounded by two (RT_Pb) and three (ART_Pb) light flashes. We show that RT_Meta and RT_Pb accuracies are close to equal, but that ART_Meta is about x2 less accurate than ART_Pb which in turn is x1.5 less accurate than ART. The latter observation fails however to reach statistical significance hence not sustaining proposals that active time estimation is more reliable than passive one. The whole dataset is accounted for by a clock-type model where duration estimation performance is limited by four noise sources (visual, clock-count, motor and proprioceptive+efference copy) plus one proper to ART_Meta task. It is proposed that the latter reflects the impossibility for the time-counting system to use the same time origin more than once. [less ▲]

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See detailOn the perceptual/motor dissociation: a review of concepts, theory, experimental paradigms and data interpretations.
Cardoso-Leite, Pedro UL; Gorea, Andrei

in Seeing and perceiving (2010), 23(2), 89-151

With its roots in Ungerleider and Mishkin's (1982) uncovering of two distinct - ventral and dorsal - anatomical pathways for the processing of visual information, and boosted by Goodale and Milner's (1992 ... [more ▼]

With its roots in Ungerleider and Mishkin's (1982) uncovering of two distinct - ventral and dorsal - anatomical pathways for the processing of visual information, and boosted by Goodale and Milner's (1992; Milner and Goodale, 1995) behavioral study of patients with lesions of either of these pathways, the perception-action dissociation became a standard reference in the sensorimotor literature. Here we present briefly the anatomical, neuropsychological and, more extensively, the psychophysical evidence favoring such dissociation and pit it against counteracting evidence as well as against potential methodological and conceptual pitfalls. We also discuss classes of models accounting for a number of 'dissociation' results and conclude that the most general and parsimonious one posits the existence of one single processing stream that accumulates information up to a decision criterion modulated by stimulation conditions, response mode (motor vs. verbal/perceptual), task constraints (speeded vs. free time responses) and the nature of the task (detection, discrimination, temporal order judgment, etc.). The reviewed evidence is not meant to refute or validate the hypothesis of a perceptual-motor dissociation. Rather, its main objective is to show that, beyond its self-evidence, such dissociation is difficult if not impossible to test. [less ▲]

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See detailComparison of perceptual and motor latencies via anticipatory and reactive response times.
Cardoso-Leite, Pedro UL; Mamassian, Pascal; Gorea, Andrei

in Attention, perception & psychophysics (2009), 71(1), 82-94

To compare the timing of perceptual and motor decisions, distinct tasks have been designed, all of which have yielded systematic differences between these two moments. These observations have been taken ... [more ▼]

To compare the timing of perceptual and motor decisions, distinct tasks have been designed, all of which have yielded systematic differences between these two moments. These observations have been taken as evidence of a sensorimotor dissociation. Inasmuch as the distinction between perceptual and motor decision moments is conceptually warranted, this conclusion remains debatable, since the observed differences may reflect the dissimilarity between the stimulations/tasks used to assess them. Here, we minimize such dissimilarities by comparing response time (RT) and anticipatory RT (ART), an alternative technique with which to infer the relative perceptual decision moments. Observers pressed a key either in synchrony with the third of a sequence of three stimuli appearing at a constant pace (ART) or in response to the onset of this third stimulus presented at a random interval after the second (RT). Hence, the two stimulation sequences were virtually identical. Both the mean and the variance of RT were affected by stimulus intensity about 1.5 times more than were the mean and the variance of ART. Within the framework of two simple integration-to-bound models, these findings are compatible with the hypothesis that perceptual and motor decisions operate on the same internal signal but are based on distinct criteria, with the perceptual criterion lower than the motor one. [less ▲]

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See detailComparison of perceptual and motor decisions via confidence judgments and saccade curvature.
Cardoso-Leite, Pedro UL; Gorea, Andrei

in Journal of neurophysiology (2009), 101(6), 2822-36

This study investigated the effects on perceptual and motor decisions of low-contrast distractors, presented 5 degrees on the left and/or the right of the fixation point. Perceptual decisions were ... [more ▼]

This study investigated the effects on perceptual and motor decisions of low-contrast distractors, presented 5 degrees on the left and/or the right of the fixation point. Perceptual decisions were assessed with a yes/no (distractor) detection task. Motor decisions were assessed via these distractors' effects on the trajectory of an impending saccade to a distinct imperative stimulus, presented 10 degrees above fixation 50 ms after the distractor(s). Saccade curvature models postulate that distractors activate loci on a motor map that evoke reflexive saccades and that the distractor evoked activity is inhibited to prevent reflexive orienting to the cost of causing a saccade curvature away from the distractor. Depending on whether or not each of these processes depends on perceptual detection, one can predict the relationships between saccades' curvature and perceptual responses (classified as correct rejections, misses, false alarms, and hits). The results show that saccades curve away from distractors only when observers report them to be present. Furthermore, saccade deviation is correlated (on a trial-by-trial basis) with the inferred internal response associated with the perceptual report: the stronger the distractor-evoked perceptual response, the more saccades deviate away from the distractor. Also in contrast with a supersensitive motor system, perceptual sensitivity is systematically higher than the motor sensitivity derived from the distributions of the saccades' curvatures. Finally, when both distractors are present (and straight saccades are expected), the sign of saccades' curvature is correlated with observers' perceptual bias/criterion. Overall the results point to a strong perceptual-motor association. [less ▲]

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See detailPerceptual criterion and motor threshold: a signal detection analysis of the relationship between perception and action.
Waszak, Florian; Cardoso-Leite, Pedro UL; Gorea, Andrei

in Experimental brain research (2007), 182(2), 179-88

Although a large number of studies have demonstrated that a motor response to a visual stimulus is, at least to some extent, independent of the perceptual response, little effort has been spent on the ... [more ▼]

Although a large number of studies have demonstrated that a motor response to a visual stimulus is, at least to some extent, independent of the perceptual response, little effort has been spent on the investigation of the explicit characteristics of this independency. In the present experiment, observers were presented with an S1-S2 stimulus-pair, with S1 within the threshold range and with S2 highly suprathreshold. S2 was displayed either at the same location as S1 (masked condition), or some degree to the left or right of S1 (non-masked). Both the observers' sensitivity to S1 and simple RTs elicited by the stimulus pair were jointly assessed on a trial-by-trial basis. Response times decreased with increasing S1 contrast for perceptual Hits both when S1 was masked by S2 and when it was not, but for Misses only when S1 was masked, though to a lesser extent than for Hits. When RTs are collapsed across perceptual Hits and Misses for any given S1-contrast, they were independent of whether S1 was masked or not. The data indicate that the motor system has a fixed, high-energy threshold, whereas the perceptual system has a d'-dependent criterion that can either be higher or lower than the motor threshold-depending on the particular conditions. [less ▲]

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See detailTemporal order judgment and simple reaction times: evidence for a common processing system.
Cardoso-Leite, Pedro UL; Gorea, Andrei; Mamassian, Pascal

in Journal of vision (2007), 7(6), 11

We present a simple reaction time (RT) versus temporal order judgment (TOJ) experiment as a test of the perception-action relationship. The experiment improves on previous ones in that it assesses for the ... [more ▼]

We present a simple reaction time (RT) versus temporal order judgment (TOJ) experiment as a test of the perception-action relationship. The experiment improves on previous ones in that it assesses for the first time RT and TOJ on a trial-by-trial basis, hence allowing the study of the two behaviors within the same task context and, most importantly, the association of RT to "correct" and "incorrect" TOJs. RTs to pairs of stimuli are significantly different depending on the associated TOJs, an indication that perceptual and motor decisions are based on the same internal response. Simulations with the simplest one-system model (J. Gibbon & R. Rutschmann, 1969) using the means and standard deviations of the RT to stimuli presented in isolation yield excellent fits of the mean RT to these increments when presented in sequence and moderately good fits of the RT when classified according to the TOJ categories. The present observation that the point of subjective simultaneity for stimulus pairs is systematically smaller than the difference in RT to each of the two increments in the same pairs pleads, however, in favor of distinct decision criteria for perception and action with the former below the latter. For such a case, standard one-system race models require that the internal noise associated with the TOJ be less than the one associated with the RT to the same stimulus pair. The present data show the reverse state of affairs. In short, data and simulations comply with "one-system-two-decision" models of perceptual and motor behaviors, while prompting further testing and modeling to account for the apparent discrepancy between the ordering of the two decisions. [less ▲]

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