The long and the short of it: Spatial statistics at fixation vary with saccade amplitude and task

Abstract

We recorded over 90,000 saccades while observers viewed a diverse collection of natural images and measured low level visual features at fixation. The features that discriminated between where observers fixated and where they did not varied considerably with task, and the length of the preceding saccade. Short saccades (<8 degrees) are image feature dependent, long are less so. For free viewing, short saccades target high frequency information, long saccades are scale-invariant. When searching for luminance targets, saccades of all lengths are scale-invariant. We argue that models of saccade behaviour must account not only for task but also for saccade length and that long and short saccades are targeted differently.

Contextual guidance of eye movements and attention in real-world scenes: The role of global features in object search.

“…Visual search tasks have been found to exhibit more long-amplitude saccades than free viewing of natural images (on average, about 3°for search and 4°f or scene perception; Rayner, 1998; see Table 1; see also Tatler, Baddeley, & Vincent, 2006). The counting search tasks resulted in an averaged saccade length of 3°.…”

Visual orienting in dynamic broadband (1/f) noise sequences

“…This difference is equally as minor as that measured in another study for static images, which compared search versus free-viewing behavior (Tatler et al, 2006). (Because of the same small difference, we considered the free-viewing behavior in our noise movies-as was carried out in Experiment 1-as analogous to free-viewing behavior in static scenes.…”

“…fixated movie patches with a set of randomly collected movie patches. This analysis was done analogously to the analysis carried out for scene-fixation studies, in which a gaze prediction for real-world scenes is sought (see, e.g., Carmi & Itti, 2006;Parkhurst & Niebur, 2003;Reinagel & Zador, 1999;Tatler et al, 2006;Vig, Dorr, & Barth, 2009). They typically used (static) images of real-world scenes while observers performed free viewing.…”

“…From scenefixation studies, it is known that there exists a preference for high contrasts (see, e.g., Parkhurst & Niebur, 2003;Reinagel & Zador, 1999;Tatler, Baddeley, & Vincent, 2006). One may therefore wonder whether this contrast preference also exists in a mere 1/f display (in our case, a movie).…”

Eye movements during scene viewing: Evidence for mixed control of fixation durations

“…Most recent research on eye movement control in scenes has focused on the placement of fixations (e.g., Itti & Koch, 2000;Parkhurst & Niebur, 2003;Tatler, Baddeley, & Vincent, 2006;Torralba, Oliva, Castelhano, & Henderson, 2006;Underwood & Foulsham, 2006). Far less research has focused on the control of fixation duration (Henderson, 2003).…”