Spatial and directional tuning of serial dependence for tracking eye movements.

An attractive influence of past sensory experience on current behavior has been observed in many domains ranging from perceptual decisions to motor responses. However, it is unclear what sort of information is integrated across trials, especially for oculomotor behavior. Here we provide a detailed investigation of the spatial and directional tuning of serial dependence for oculomotor tracking.

A simple optical flow model explains why certain object viewpoints are special.

A core challenge in perception is recognizing objects across the highly variable retinal input that occurs when objects are viewed from different directions (e.g. front versus side views).

The eyes anticipate where objects will move based on their shape.

Imagine staring into a clear river, starving, desperately searching for a fish to spear and cook. You see a dark shape lurking beneath the surface. It doesn't resemble any sort of fish you've encountered before - but you're hungry.

Mental object rotation based on two-dimensional visual representations.

The discovery of mental rotation was one of the most significant landmarks in experimental psychology, leading to the ongoing assumption that to visually compare objects from different three-dimensional viewpoints, we use explicit internal simulations of object rotations, to 'mentally adjust' one object until it matches the other. These rotations are thought to be performed on three-dimensional representations of the object, by literal analogy to physical rotations. In particular, it is thought that an imagined object is continuously adjusted at a constant three-dimensional angular rotation rate from its initial orientation to the final orientation through all intervening viewpoints.

Serial dependence for oculomotor control depends on early sensory signals.

To create an accurate percept of the world, the visual system relies on past experience and prior assumptions. For example, although the retinal projection of an object moving in depth changes drastically, we still perceive the object at a constant size and velocity. Consequently, if we see the same object with a constant retinal size at two different depth levels, the perceived size differs (illustrated by the Ponzo illusion).

Humans represent the precision and utility of information acquired across fixations.

Our environment contains an abundance of objects which humans interact with daily, gathering visual information using sequences of eye-movements to choose which object is best-suited for a particular task. This process is not trivial, and requires a complex strategy where task affordance defines the search strategy, and the estimated precision of the visual information gathered from each object may be used to track perceptual confidence for object selection. This study addresses the fundamental problem of how such visual information is metacognitively represented and used for subsequent behaviour, and reveals a complex interplay between task affordance, visual information gathering, and metacogntive decision making.

A review of interactions between peripheral and foveal vision.

Visual processing varies dramatically across the visual field. These differences start in the retina and continue all the way to the visual cortex. Despite these differences in processing, the perceptual experience of humans is remarkably stable and continuous across the visual field.

Stronger saccadic suppression of displacement and blanking effect in children.

Humans do not notice small displacements to objects that occur during saccades, termed saccadic suppression of displacement (SSD), and this effect is reduced when a blank is introduced between the pre- and postsaccadic stimulus (Bridgeman, Hendry, & Stark, 1975; Deubel, Schneider, & Bridgeman, 1996). While these effects have been studied extensively in adults, it is unclear how these phenomena are characterized in children. A potentially related mechanism, saccadic suppression of contrast sensitivity-a prerequisite to achieve a stable percept-is stronger for children (Bruno, Brambati, Perani, & Morrone, 2006).

The spatial and temporal properties of attentional selectivity for saccades and reaches.

The preparation and execution of saccades and goal-directed movements elicits an accompanying shift in attention at the locus of the impending movement. However, some key aspects of the spatiotemporal profile of this attentional shift between eye and hand movements are not resolved. While there is evidence that attention is improved at the target location when making a reach, it is not clear how attention shifts over space and time around the movement target as a saccade and a reach are made to that target.

Transsaccadic integration benefits are not limited to the saccade target.

Across saccades, humans can integrate the low-resolution presaccadic information of an upcoming saccade target with the high-resolution postsaccadic information. There is converging evidence to suggest that transsaccadic integration occurs at the saccade target. However, given divergent evidence on the spatial specificity of related mechanisms such as attention, visual working memory, and remapping, it is unclear whether integration is also possible at locations other than the saccade target.

Transsaccadic integration is dominated by early, independent noise.

Humans are able to integrate pre- and postsaccadic percepts of an object across saccades to maintain perceptual stability. Previous studies have used Maximum Likelihood Estimation (MLE) to determine that integration occurs in a near-optimal manner. Here, we compared three different models to investigate the mechanism of integration in more detail: an early noise model, where noise is added to the pre- and postsaccadic signals before integration occurs; a late-noise model, where noise is added to the integrated signal after integration occurs; and a temporal summation model, where integration benefits arise from the longer transsaccadic presentation duration compared to pre- and postsaccadic presentation only.

Optimal trans-saccadic integration relies on visual working memory.

Saccadic eye movements alter the visual processing of objects of interest by bringing them from the periphery, where there is only low-resolution vision, to the high-resolution fovea. Evidence suggests that people are able to achieve trans-saccadic integration in a near-optimal manner; however the mechanisms underlying integration are still unclear. Visual working memory (VWM) is sustained across a saccade, and it has been suggested that this memory resource is used to store and compare the pre- and post- saccadic percepts.

Attention modulates trans-saccadic integration.

With every saccade, humans must reconcile the low resolution peripheral information available before a saccade, with the high resolution foveal information acquired after the saccade. While research has shown that we are able to integrate peripheral and foveal vision in a near-optimal manner, it is still unclear which mechanisms may underpin this important perceptual process. One potential mechanism that may moderate this integration process is visual attention.

The profile of attention differs between locations orthogonal to and in line with reach direction.

People make movements in a variety of directions when interacting with the world around them. It has been well documented that attention shifts to the goal of an upcoming movement, whether the movement is a saccade or a reach. However, recent evidence suggests that the direction of a movement may influence the spatial spread of attention (Stewart & Ma-Wyatt, 2015, Journal of Vision, 15(5), 10).

The spatiotemporal characteristics of the attentional shift relative to a reach.

While the attentional shift preceding a saccadic eye movement has been well documented, the mechanisms surrounding the attentional shift preceding a reach are not well understood. It is unknown whether these mechanisms may be the same as those used in perceptual tasks, or those used in the planning of a saccade. We mapped the spatiotemporal properties of attention relative to a reach to determine the time course of attentional facilitation for hand movements alone.