Abstract:
Eye movement investigations have long been crucial for building a comprehensive understanding of the cognitive and perceptual processes that support reading and other language processes because of their naturalness and great temporal precision (reviewed in Rayner, Pollatsek, Ashby & Clifton, 2012). Indeed, most of what we know about psycholinguistics has been deeply informed by eye movement reading data, including the fundamentals of word processing, contextual effects, grammatical interpretation, and higher-level aspects of language such as figurative or emotional effects on language.

Of relevance here, much of this work has historically focused on university-aged monolingual (or presumed monolingual) readers. However, in recent years, eye movement studies of reading have been extended to a variety of “special” populations, many of which are actually quite common. In this talk, I present some of the work from my laboratory that has used eye movement measures to study a variety of psycholinguistic questions about reading in different populations. These populations include healthy bilingual younger and older adults, as well as neuropathic populations, such as people living with schizophrenia or dyslexia. Across these populations, I will focus on the interplay between local word-level processing and more global influences of context, such as what arises from variations in sentential constraint or the interpretive demands of figurative language.

Abstract:
While the deficits consecutive to the right temporo-parietal junction damage concern the spatio-temporal integration of the visual information sampled by eye movements, the deficits consecutive to the dorsal posterior parietal cortex (PPC) damage have in common to concern peripheral vision. In particular, bilateral dorsal PPC damage leads to a reduced search window when spatial binding of lines is needed, a specific visual search deficit for symbols which has also been observed in individuals with a visuo-attentional form of developmental dyslexia. One hypothesis we have put forward is that the dorsal PPC actively compensates for the under-representation of peripheral vision that accompanies central magnification.

Abstract:
Endogenous (voluntary) and exogenous (involuntary) covert spatial attention alter performance and appearance in many basic visual tasks mediated by contrast sensitivity and spatial resolution, without accompanying eye movements. Presaccadic attention allocated to the location of the saccade’s target (in the absence of attention cues) also modulates performance. For instance, akin to covert attention, while planning an eye movement presaccadic attention improves performance and increases perceived contrast at the saccade target location. Critically, these modulations change the processing of feature information. Using a psychophysical reverse correlation approach, we found that saccade preparation selectively narrows orientation tuning and enhances the gain of high spatial frequency information at the upcoming saccade location. Moreover, this frequency shift takes place automatically even when it is detrimental to the task at hand. These three studies reveal that these modulations are timelocked to saccade onset, peaking right before the eyes move. Crucially, merely deploying covert spatial attention without preparing a saccade alters neither performance nor appearance within the same temporal interval. We propose that saccade preparation may support transaccadic integration by reshaping the representation of the saccade target to be more fovea-like just before saccade onset. I will discuss similarities and differences among covert–endogenous and exogenous–spatial, feature-based and presaccadic attention, with regard to their temporal dynamics, gain and tuning properties.

Abstract:
We move our eyes two or three times every second, in order to get the right information at the right time for the behaviours we engage in. Where we look is determined by a mixture of low-level information, higher-level understanding, internal goals, and biases to view scenes in particular ways. Computational models are emerging that include factors from the full range of this mixture and do a reasonable job at explaining where people look in scenes. However, a complete understanding of how we gather information from scenes must encompass not only where people look but also when they move their eyes. Studies of temporal allocation of gaze in scene viewing are far fewer in number than studies of spatial allocation and theories assume separate mechanisms for controlling the spatial and temporal allocation of gaze.

I will review current understanding of spatial and temporal gaze allocation in scene viewing and present our recent decision-based model of scene viewing that encompasses both when and where the eyes move. Our model asserts that each decision to move the eyes is an evaluation of the relative benefit expected from moving the eyes to a new location compared with that expected by continuing to fixate the current target. The eyes move when the evidence that favors moving to a new location sufficiently outweighs that favoring staying at the present location. This single decision process can explain both when and where people look in scenes.

Abstract:
Over the past 25 years, it has become clear that the lateral intraparietal area (LIP) and the frontal eye field (FEF) play important roles in guiding saccades. Yet despite this focus, it is still unclear how the two areas differ: neurons in each area often behave quite similarly in standard search or oculomotor tasks. Using a visual foraging task, in which animals are free to move their eyes as they please and from which we can record activity across multiple eye movements within a trial, we have identified numerous differences between the areas. I will discuss the implications of these results and suggest that the areas are part of a recurrent system in which additional processing occurs between LIP and some FEF neurons, while others provide feedback to LIP about upcoming and previous saccades.

Abstract:
The existence of a central fovea, the small retinal region with high analytical performance, is arguably the most prominent design feature of the primate visual system. This centralization comes along with the corresponding capability to move the eyes to reposition the fovea continuously. Past research on visual perception was mainly concerned with foveal vision while the observers kept their eyes stationary. Research on the role of eye movements in visual perception emphasized their negative aspects, for example, the active suppression of vision before and during the execution of saccades. But is the only benefit of our precise eye movement system to provide high acuity of the small foveal region, at the cost of retinal blur during their execution? In this review, I will compare human visual perception with and without saccadic and smooth pursuit eye movements to emphasize different aspects and functions of eye movements. I will show that the interaction between eye movements and visual perception is optimized for the active sampling of information across the visual field and for the calibration of different parts of the visual field. The movements of our eyes and visual information uptake are intricately intertwined. The two processes interact to enable an optimal perception of the world, one that we cannot fully grasp by doing experiments where observers are fixating a small spot on a display.