Assignment of credit and constraints on eye movement learning - ANR project ACES

Keywords : Motor learning - Assignment of credit - Contextual learning - Eyetracking - Saccadic adaptation

Effects of the nature of the stimulus on contextual saccadic adaptation

Contextual saccadic adaptation is studied with a variant of the double step saccade adaptation paradigm, in which the direction of the intra-saccadic step is signaled by two different contexts. This allows to simultaneously inducing two distinct saccadic adaptations. Effective contextual adaptation occurs when the amplitude of the first step serves as context, but not when using the target color or shape.

All experimental sessions are based on the same contextual adaptation procedure, the only difference being the context used. We tested six different contexts : the duration of a visual stimulus, the lateralization of a sound in space, the statistical regularity across trials, and a symbolic cue, as well as the amplitude of the first step and the target color and shape to compare our results with previous studies.

We collected data from 80 participants. Fisher's test allowed us to show an effect of the context with the amplitude of the first step condition in all participants, with the symbolic cue for one participant (out of 4) and with the target color and shape for one participant (out of 4) . The Kolmogorov-Smirnov distance confirms a strong contextual effect for the amplitude, but not for the other contexts.

The lack of contextual learning reveals that predicting the intra-saccadic step is relatively difficult and strongly depends on the nature of the context, even for highly salient contexts that are perfectly correlated with the ISS. The correlation between context and ISS is not sufficient for learning, even for non-visual contexts. A similar effect, termed selective learning or biological constraints on learning, has been previously reported in pavlovian and operant conditioning animal studies.