Stimulus-driven saccades are characterized by an invariant undershooting bias: no evidence for a range effect

Abstract

Saccade endpoints are most frequently characterized by an undershooting bias. Notably, however, some evidence suggests that saccades can be made to systematically under- or overshoot a target based on the magnitude of the eccentricities within a given block of trials (i.e., the oculomotor range effect hypothesis). To address that issue, participants completed stimulus-driven saccades in separate blocks of trials (i.e., proximal vs. distal) that entailed an equal number of targets but differed with respect to the magnitude of their eccentricities. In the proximal block, target eccentricities were 3.0°, 5.5°, 8.0°, 10.5° and 13.0°, whereas in the distal block target eccentricities were 10.5°, 13.0°, 15.5°, 18.0° and 20.5°. If the range effect represents a tenable hypothesis, then the magnitude of target eccentricities within each block should selectively influence saccade endpoint bias. More specifically, the eccentricities common to the proximal and distal blocks (i.e., 10.5° and 13.0°) should elicit a systematic under- and overshooting bias, respectively. Results for the proximal and distal blocks showed a reliable undershooting bias across target eccentricities, and a direct comparison of the common eccentricities indicated that the undershooting bias was not modulated between blocks. Moreover, our results show that the presence of online target vision did not influence the undershooting bias. Thus, the present findings provide no support for an oculomotor range effect; rather, results evince the mediation of saccades via a control strategy that minimizes movement time and/or the energy requirements of the response.

Target frequency influences antisaccade endpoint bias: Evidence for perceptual averaging

“…Thus, the undershooting bias cannot be attributed to a speed/accuracy trade-off in movement planning (c.f. Abrams, Meyer, & Kornblum, 1989;Gillen & Heath, in press;Gillen, Weiler, & Heath, 2013; but see Kowler & Blaser, 1995). Additionally, that the undershooting bias was equivalent across the control, proximal-and distal-weighting conditions is consistent with the assertion that prosaccade sensorimotor transformations are mediated largely independent of top-down cortical processes via retinotopically organized motor maps in the superior colliculus (Wurtz & Albano, 1980).…”

“…Notably, the direct spatial relations between stimulus and response permit absolute visual information to mediate prosaccade sensorimotor transformation via retinotopically organized motor maps within the superior colliculus (Wurtz & Albano, 1980). In spite of the direct spatial relations, primary and secondary (i.e., corrective) prosaccades typically undershoot veridical target location (Abrams, Meyer, & Kornblum, 1989;Becker & Fuchs, 1969;Deubel, Wolf, & Hauske, 1986;Gillen, Weiler, & Heath, 2013;Prablanc & Jeannerod, 1975;Robinson, 1964;Weber & Daroff, 1971). In particular, prosaccades exhibit a 10% undershooting bias that is thought to reflect an invariant control strategy that minimizes saccade flight time (i.e., saccadic flight time hypothesis: Harris, 1995) and/or the energy requirements of the response (i.e., energy minimization hypothesis: Becker, 1989).…”

Adaptation of naturally paced saccades

“…2A; repeatedmeasures ANOVA, F(1,8) ϭ 0.08, P ϭ 0.79], but there was a main effect of target amplitude on gain [F(3,24) ϭ 26.4, P Ͻ 0.001]. This "range effect" of target amplitudes on saccade gain is well established in the literature (e.g., Abrams et al 1989;Kapoula and Robinson 1986), despite recent challenge to it (Gillen et al 2013). The normality of gain was convenient and reassuring for our aim of studying saccade gain adaptation at faster pacing but was by no means a foregone conclusion.…”

Optimal planning of eye movements

“…27 A limitation of ideal-observer theory is that performing sensory inference by 28 itself does not prescribe an action, i.e. information about s in the end needs 29 to be used to decide for an appropriate action, e.g. whether to flee.…”

“…a bounded actor (see Materials). We added additive costs for 150 longer saccade amplitude (as they lead to longer scanpath duration 24 and higher 151 endpoint variability 25 , which humans have been shown to minimize 26 ), used 152 foveated versions of the shapes to account for the decline of visual acuity in 153 peripheral vision 27 , and accounted for the often reported fact, that human sac-154 cades undershoot their target 28,29 . We used the sum of squared errors between 155 our model prediction and our data to compute the BIC for each model.…”