Spatial and/or temporal adjustments of scanning behavior to visibility changes

Attention, Information Processing, and Eye Movement Control

“…However, their theoretical proposal marks a renaissance of ideas close to the classic notion of perceptual span control, which, although very appealing, has unfortunately been shown to be not in harmony with a substantial body of empirical evidence. First, there are studies that manipulated visual parameters, such as viewing distance (O'Regan, Lévy-Schoen & Jacobs, 1983), target-background similarity and letter visibility (Jacobs 1986, Jacobs & O'Regan 1987 using psychophysical methods. In these studies the concomitant changes in saccade extent or fixation duration to be expected from perceptual span control were not observed.…”

Patterns of Activity in the Human Frontal and Parietal Cortex Differentiate Large and Small Saccades

“…The oculomotor apparatus is thus capable of producing saccades of a wide range of amplitudes depending on the context (Yarbus, 1967; Bahill et al, 1975; Leigh and Zee, 1999; Pelz and Canosa, 2001; Borji and Itti, 2014). Furthermore, a number of studies indicate that the size of saccades is closely linked to visual and cognitive processing (Jacobs and O’Regan, 1987; Land et al, 1999; Tatler et al, 2006). Indeed, while small (<10° of visual angle) saccades are more frequent, their proportion, relative to large saccades varies with the task, indicating a functional distinction between the two types of saccades (Tatler et al, 2006).…”

“…Some authors have proposed that visual exploration with large saccades corresponds to a pre-attentive or “ambient” scanning mode, while small saccades would be associated with a more intensive and detailed “focal” processing (Pelz and Canosa, 2001; Unema et al, 2005; Tatler et al, 2006; Over et al, 2007). This distinction appears to be present very early on in development (as young as 2 years old; Helo et al, 2014), and is also associated with the visual features and duration of successive fixations (Jacobs and O’Regan, 1987). Even for visually guided reflexive saccades (i.e., toward a suddenly appearing visual target), the characteristics of saccades depends upon eccentricity, with smaller saccades having better accuracy than larger saccades, which tend to be hypometric, more variable and faster (Frost and Poppel, 1976; Abrams et al, 1989).…”

Eye movements during search and detection in comparative visual search

“…For example, Just and Carpenter (1976) analyzed the scan paths of observers making same/different judgments on rotated figures and used the frequency and position of fixations that switch between the figures to divide trials into stages of search, comparison, and confirmation. In addition to the location of fixations, changes in fixation duration are useful markers of a change in strategy or processing, since they increase with the difficulty of the foveal task (Gould, 1967(Gould, , 1973Hooge & Erkelens, 1998;Jacobs, 1986;Jacobs & O'Regan, 1987) and vary between processes such as encoding and comparing (Gould, 1967;Gould & Peeples, 1970).…”