The control of saccadic adaptation: implications for the scanning of natural visual scenes

Abstract

Accurate scanning of natural scenes depends on: (1) attentional selection of the target; (2) spatial pooling over the attended target to compute the precise landing position; and (3) adaptive modification of saccades to ensure saccadic accuracy. The present experiments studied adaptation. Adaptive modifications were induced by displacing the target during saccades. Adaptation was found to be: (1) similar for a small target point and a large target circle, despite the differences in the spatial pattern of landing position errors for each; (2) unaffected by instructions to look part way to the target, even though such instructions altered landing position error relative to the target; and (3) insensitive to symbolic cues disclosing the direction of the intra-saccadic displacement. Briefly delaying the presentation of the post-saccadic target greatly reduced adaptation. Neither corrective saccades, nor the position errors that trigger corrections, were involved in adaptation because corrective saccades rarely occurred with a large target circle even though the circle produced as much adaptation as the single point. Taken together, the results do not support the traditional notion that post-saccadic retinal position error controls adaptation. We propose that adaptation relies on a comparison of the actual post-saccadic retinal image with the post-saccadic image that would be predicted based on a representation of the planned saccade. Such a comparison: (1) is consistent with our results; (2) may be more effective than retinal position error in controlling adaptation in natural visual scenes containing large targets and backgrounds; and (3) is similar to the motion-based adaptive mechanisms associated with the VOR. Similarity between the adaptive control of saccades and adaptive control of the VOR raises the possibility that the most important role of saccadic adaptation may be the coordination of eye and head movements during shifts of gaze.

Visual cues that are effective for contextual saccade adaptation

“…The presumed function of saccade adaptation is typically as a pure recalibration mechanism, and why might this be interested in visual properties of targets? Previous studies testing visual properties such as shape and color (Deubel 1995) or shape alone (Bahcall and Kowler 2000) have not found significant evidence of contextual saccade adaptation. Our lack of contextuality from color and shape cues (experiment 3) are, thus, entirely consistent with these previous reports, as well as the impotence of color and shape in contextual adaptation of smooth pursuit (Takagi et al 2000), and arm movement (Howard et al 2013).…”

“…We found that intrasaccadic steps of either flickering or nonflickering targets led to different adaptations to the two different target types, providing both visual contexts were frequently intermixed (Herman et al 2009). The only other studies reporting visual contexts found that color and shape were largely ineffective cues, as adaptation was broadly similar for red circles and green crosses with different intrasaccadic perturbations (Deubel 1995) or for diamonds vs. squares (Bahcall and Kowler 2000). The methods were so different that it is difficult to compare the three studies.…”

“…Adaptation of our rapid, gaze reorienting, saccadic eye movements shares many similarities with adaptation of rapid arm movements, and concepts and data from one modality are often translatable to the other (Herman et al 2013a). Examples of these overlaps include the use of sensory prediction error signals (Bahcall and Kowler 2000;Wolpert et al 1998), multiple timescales of motor memory (Kording et al 2007;Joiner and Smith 2008), and adaptation that is context specific (Pelisson et al 2010;Wolpert et al 1998).…”

Eye Movement Analysis during Activities of Daily Living (ADL) among Fully Sighted School Children

“…This suggests that adaptation process may not affected the eye movement parameters when performing ADL that only using the same arrangement. This is because the adaptation process depends on the comparison of two different images when an activity is repeated (Bahcall & Kowler 2000). Besides that, previous study reported that eye movement were also influence the visual habit.…”

Scandinavian Journal of Psychology*

“…Those are relatively ballistic movements of the eye; their vectors and landing points are computed beforehand and once the command for the saccade has been made, relatively little influence can be had on the direction and landing point of the saccade (Leigh & Zee, 1999;Goldberg, 2000;Sparks, 2002); although there are examples of how shifting the intended landing point during the eye movement can result in slight online modifications of the saccade landing point (an effect known as saccadic adaptation, see e.g. Bahcall & Kowler, 2000;McLaughlin, 1967) and modification can occur for landing points based on previous target history, while everything else remains constant (Edelman, Kristjánsson & Nakayama, 2001;He & Kowler, 1989).…”