|Control of Human Eye Movements by Operant Contingencies: Current Research and Theory|
|Tuesday, November 14, 2017|
|2:00 PM–3:50 PM|
|Loft A, Niveau 3|
|Area: EAB; Domain: Basic Research|
|Chair: Celine Paeye (Université Paris Descartes)|
|Discussant: Peter Endemann (University of São Paulo)|
|Abstract: Ocular saccades and smooth pursuit are the eye movements we use when we explore our environment, look for information, or track moving objects. These gaze shifting movements place the retinal image of a target on the fovea (the small high-acuity area of the retina), allowing the visual system to perceive the fine details of the visual environment. Therefore, eye movements have sometimes been described and assessed as observing responses (i.e., responses that lead to exposure to discriminative stimuli, e.g. Tomanari et al., 2007). In addition, saccade and pursuit are known to have adaptive properties and to respond to changes occurring in the visual system or in the environment. This symposium brings together four researchers to discuss the last findings and theorizing on the control of eye movements by reinforcement contingencies in human adults. The presentations span the range of studies from anticipatory smooth pursuit to various saccadic properties, including latencies of single saccades and gaze allocation during visual search tasks. These recent studies indicate that the operant learning theory provides a valid alternative to contemporary computational models of motor control and decision-making.|
|Instruction Level: Advanced|
|Keyword(s): Eye movements, Ocular saccades, Smooth pursuit, Vision|
|Anticipatory Smooth Eye Movements are Modulated by Reinforcement Contingencies|
|Jean-Bernard Damasse (Aix Marseille Universitï¿½, CNRS), Laurent Perrinet (Aix Marseille Université, CNRS), Laurent Madelain (Aix Marseille Université, CNRS ; Université Lille Nord de France), Jeremie Jozefowiez (Université de Lille), ANNA MONTAGNINI (Aix Marseille Universitï¿½, CNRS)|
|Abstract: Despite their relative simplicity, voluntary goal-directed eye movements are often used as a model of sensorimotor decision-making, as they generally rely on the dynamic selection of one out of several potentially relevant targets and they have proven extremely adaptive to the context. Importantly, visually-guided eye movements are modulated by their behavioral outcomes (Madelain, 2011; Montagnini, 2005). Here we study and model anticipatory smooth pursuit eye movements (aSPEM) performed ahead of target onset when the forthcoming target motion properties are partly predictable. The effects of reinforcement contingencies on aSPEM can be considered as a particular case of credit assignment problem (Kaelbling, 1996), indicating the difficult match between a particular property of a behavior and the outcome. In a baseline direction-bias task we manipulated the probability of target direction. We then modified the task by setting an implicit eye-velocity criterion during anticipation. The nature of the following trial-outcome (reward or punishment) was contingent to the criterion-matching during estimate of aSPEM. We observed a dominant graded effect of the direction-bias and a small modulatory effect of contingent reinforcement on aSPEM velocity. A yoked-control paradigm corroborated this result showing a strong reduction in anticipatory behavior when the reward/punishment schedule was not contingent (Damasse, 2016).|
|Control of Saccadic Latencies in a Concurrent Interval Reinforcement Schedule|
|CÉCILE VULLINGS (Université Lille Nord de France), Laurent Madelain (Université Lille Nord de France;Aix-Marseille CNRS)|
|Abstract: Saccadic latencies are conventionally viewed as reflecting the accumulation of information during decision-making process. However, we have previously shown that latency distributions may be strongly affected by reinforcement contingencies (Madelain et al., 2007). Here, we probe the effect of concurrent schedules on the control of saccadic latencies.
Six human adults made saccades within 80-300ms following the horizontal displacement of a target. For each subject, we selected two classes of latencies, ‘short’ and ‘long’, using the first and last quartiles of baseline distribution (e.g. [80;151]ms and [185;300]ms respectively). Applying random interval reinforcement schedules, we then concurrently reinforced each class in three blocked conditions (approximately 20000 saccades per subject) such that the relative frequencies of reinforcing ‘short’ versus ‘long’ latencies were either 9/1, 1/9 or 1/1.
We observed modifications of latency distributions depending on the reinforcement contingency in force: distributions shifted toward the shorter or longer values or became strongly bimodal and the relative proportion of latencies matched the relative proportion of reinforcers earned from each option (sensitivity up to 0.95).
Our results indicate that learned contingencies might considerably affect the allocation of saccades in time, and provide strong evidence of a control of saccadic latencies extending well beyond information accumulation.|
|Finding a Target Reinforces Saccadic Eye Movements in Visual Search|
|CELINE PAEYE (Université Lille Nord de France ; Giessen Universität ; Université Paris Descartes), Laurent Madelain (Université Lille Nord de France ; Aix-Marseille Université, CNRS), Alexander Schütz (Giessen Universität ; Marburg Universtität), Karl Gegenfurtner (Giessen Universität)|
|Abstract: Arbitrary, non-visual consequences are known to affect eye movements in simple visual tasks. We designed a new paradigm to test whether finding a visual target can also be effective to reinforce saccadic eye movements during complex visual search tasks.
Human adults were instructed to search for a target that was not visible at the beginning of the trial. We used gaze-contingent displays to present the target immediately after saccades that met various criteria.
In one study the target was presented more often after saccades into a specific quadrant. Between baseline trials (without target) and trials at the end of learning, the proportions of saccades towards this quadrant nearly tripled. Moreover, participants matched their relative rates of saccades to the relative rates of targets, which was consistent with the generalized matching law (sensitivity: 1.21, R²: 0.94). In another study, the target was visible only after saccades of rare amplitude (to increase variability) and then after saccades of frequent amplitude (to decrease variability). U values, or ‘uncertainty’, increased by 54.89% on average and then decreased by 41.21%.
These findings show that seeing a target controls saccadic properties, including variability, and confirm that operant learning can guide visual search behavior.|
|Operant Control of Human Eye Movements|
|LAURENT MADELAIN (Université Lille Nord de France; Aix-Marseille Université, CNRS)|
|Abstract: Saccade and smooth pursuit are the eye movements used by primates to shift gaze. We propose that these responses are operant behaviors controlled by their consequences on performance of visually guided tasks: in real life these movements are controlled by an enhanced clarity of a visual target, allowing adapted visually guided behaviors which act as reinforcers. It is therefore difficult to disentangle the visual discriminative stimulus (clarity of the visual target stimulus) from the reinforcing consequences (the task that depends on the clear perception of the visual stimulus) and it is not surprising that the visual properties of the target are conventionally regarded as the controlling signals for gaze shifting movements. In the laboratory however, one may use non-visual reinforcers to induce changes in response topography and study the operant properties of eye movements. We applied this approach to probe the effects of reinforcement on several dimensions of pursuit or saccades such as their velocities, amplitudes or reaction times, and showed that voluntary eye movements depend on reinforcement contingencies. Studying the conditions under which particular eye movement patterns might emerge from the cumulative effects of reinforcement provides critical insights about how motor responses are attuned to environmental exigencies.|