Object-location binding across a saccade: A retinotopic spatial congruency bias

Abstract

Despite frequent eye movements that rapidly shift the locations of objects on our retinas, our visual system creates a stable perception of the world. To do this, it must convert eye-centered (retinotopic) input to world-centered (spatiotopic) percepts. Moreover, for successful behavior we must also incorporate information about object features/identities during this updating – a fundamental challenge that remains to be understood. Here we adapted a recent behavioral paradigm, the “Spatial Congruency Bias”, to investigate object-location binding across an eye movement. In two initial baseline experiments, we showed that the Spatial Congruency Bias was present for both gabor and face stimuli in addition to the object stimuli used in the original paradigm. Then, across three main experiments, we found the bias was preserved across an eye movement, but only in retinotopic coordinates: Subjects were more likely to perceive two stimuli as having the same features/identity when they were presented in the same retinotopic location. Strikingly, there was no evidence of location binding in the more ecologically relevant spatiotopic (world-centered) coordinates; the reference frame did not update to spatiotopic even at longer post-saccade delays, nor did it transition to spatiotopic with more complex stimuli (gabors, shapes, and faces all showed a retinotopic Congruency Bias). Our results suggest that object-location binding may be tied to retinotopic coordinates, and that it may need to be re-established following each eye movement rather than being automatically updated to spatiotopic coordinates.

Binding object features to locations: Does the “spatial congruency bias” update with object movement?

“…One critical question is whether the Spatial Congruency Bias is a purely spatial effect reflecting low-level retinotopic input, or whether it is sensitive to more ecologically relevant information about an object's location. Recent studies from our group have found that the Spatial Congruency Bias remains in retinotopic (not spatiotopic) coordinates after a saccadic eye movement (Shafer-Skelton et al, 2017), and that the congruency bias is driven by 2D (not 3D) spatial location information (Finlayson & Golomb, 2016). However, it has long been known that one of the most compelling cues for object “sameness” is spatiotemporal contiguity (Burke, 1952; Flombaum et al, 2009; Hollingworth & Franconeri, 2009; Kahneman et al, 1992; Mitroff & Alvarez, 2007).…”

“…In a recent paper, we tested an additional manipulation of the Spatial Congruency Bias – whether it was tied to absolute (spatiotopic) locations or eye-centered (retinotopic) locations following an eye movement (Shafer-Skelton et al, 2017). The Spatial Congruency Bias was linked purely to retinotopic location; even at longer delays after the saccade (more time to update) and for objects of varying complexity (gabors, objects, and faces), there was no evidence for spatiotopic binding (Shafer-Skelton et al, 2017).…”

“…In a recent paper, we tested an additional manipulation of the Spatial Congruency Bias – whether it was tied to absolute (spatiotopic) locations or eye-centered (retinotopic) locations following an eye movement (Shafer-Skelton et al, 2017). The Spatial Congruency Bias was linked purely to retinotopic location; even at longer delays after the saccade (more time to update) and for objects of varying complexity (gabors, objects, and faces), there was no evidence for spatiotopic binding (Shafer-Skelton et al, 2017). While both paradigms found evidence against absolute-position binding, there is a difference between retinotopic (eye-centered) representations (Shafer-Skelton et al, 2017) and configural array-centered representations that survive translation and expansion to different retinotopic positions (Hollingworth & Rasmussen, 2010).…”

“…Effect sizes were calculated using Cohen's d. Trials on which subjects failed to respond, or responded with RTs greater than or less than 2.5SD of the subject's mean RT were excluded (less than 3% of trials for each experiment). Subjects who had an overall task accuracy of less than 55% (indicating non-compliance or inability to perform the task; criterion set in advance, consistent with Finlayson & Golomb, 2016; Shafer-Skelton et al, 2017) were excluded from analyses. (Reanalyzing the data without excluding these subjects did not change the patterns or conclusions.…”

“…This is a robust effect that seems to reflect an automatic influence of location information on object perception. Moreover, it is uniquely driven by location: object location biases judgments of shape, color, orientation, and even facial identity (Golomb et al, 2014; Shafer-Skelton, Kupitz, & Golomb, 2017); yet these features do not bias each other, nor do they bias judgments of location (Golomb et al, 2014). The Spatial Congruency Bias suggests that irrelevant location information is automatically encoded with and bound to other object properties, biasing their perceptual judgments.…”