Practice improves peri-saccadic shape judgment but does not diminish target mislocalization

Abstract

Visual sensitivity is markedly reduced during an eye movement. Peri-saccadic vision is also characterized by a mislocalization of the briefly presented stimulus closer to the saccadic target. These features are commonly viewed as obligatory elements of perisaccadic vision. However, practice improves performance in many perceptual tasks performed at threshold conditions. We wondered if this could also be the case with peri-saccadic perception. To test this, we used a paradigm in which subjects reported the orientation (or location) of an ellipse briefly presented during a saccade. Practice on peri-saccadic orientation discrimination led to long-lasting gains in that task but did not alter the classical mislocalization of the visual stimulus. Shape discrimination gains were largely generalized to other untrained conditions when the same stimuli were used (discrimination during a saccade in the opposite direction or at a different stimulus location than previously trained). However, performance dropped to baseline level when participants shifted to a novel Vernier discrimination task under identical saccade conditions. Furthermore, practice on the location task did not induce better stimulus localization or discrimination. These results suggest that the limited visual information available during a saccade may be better used with practice, possibly by focusing attention on the specific target features or a better readout of the available information. Saccadic mislocalization, by contrast, is robust and resistant to top-down modulations, suggesting that it involves an automatic process triggered by the upcoming execution of a saccade (e.g., an efference copy signal).perceptual learning | saccades | saccadic suppression | saccadic mislocalization | vision

Eye movement training is most effective when it involves a task-relevant sensorimotor decision

“…Each participant was randomly assigned to one of five groups (n ¼ 10 each): four training groups that were tested at least five times and one control group that was tested at least twice (see Table 1). Sample size per group is comparable to other studies investigating training effects on eye or finger movements (Dempsey-Jones et al, 2016;Porat & Zohary, 2016). Remuneration was $8 per hour for each session; a bonus of $20 was paid upon completion of all five sessions.…”

“…On the other hand, specificity depends on stimulus characteristics and task requirements. Transfer of perceptual learning from one location to another has been observed when the second location was previously sensitized via training an irrelevant task at that location (Xiao et al, 2008) or when the same stimuli were used (Porat & Zohary, 2016). Transfer across tasks, for example, from Vernier acuity and contrast detection to Snellen acuity, has been observed in patients with amblyopia (Levi & Li, 2009) and college baseball players (Deveau, Ozer, & Seitz, 2014), who even seem to improve on-field performance following such training (see also Faubert, 2013).…”

Learning to silence saccadic suppression

“…Previous work has demonstrated that perceptual learning is possible both before ( 48 ) and during ( 49 ) saccades. Porat and Zohary ( 49 ) demonstrated that shape discrimination could improve, even if the stimulus was presented during a saccade.…”

“…Empirical validation of this assumption is lacking, however, as most studies aggregate perisaccadic visual judgements (often in a small number of well-trained observers) across multiple testing sessions. Two recent studies have reported learned improvements in visual task performance following training with stimuli consistently presented before ( 48 ) or during ( 49 ) saccades. While these findings demonstrate that perceptual learning is possible around the time of saccades, the role of suppression in this process remains unclear.…”

Eye movements shape visual learning

“…One exception is the learning of new visual associations between stimuli seen across saccades (40)(41)(42)(43), but in most cases it does not appear that saccades are necessary to elicit this type of learning (39)(40)(41). Other studies have shown that perceptual learning is sensitive to spatiotopic locations defined in part by eye position (44) and that perceptual learning can improve visual sensitivity during saccades (45).…”