Inhibition of return is not a foraging facilitator in saccadic search and free viewing

Abstract

The ability to search and scan the environment effectively is a prerequisite for spatial behavior. A longstanding theory proposes that inhibition of previously attended loci (Inhibition of return; IOR) serves to facilitate exploration by increasing the likelihood to inspect new areas instead of returning to locations that have been inspected before. In this eye movement study we tested whether we could find evidence in favor of this hypothesis. Here we report that IOR does occur during search and free viewing, because we found increased fixation times preceding return saccades (eye movements that return to previously fixated locations). Meanwhile we observed no influence of IOR on the search strategy. Rather than the predicted low number we found many return saccades. Therefore, IOR does not serve as a foraging facilitator in saccadic search and free viewing. We hypothesize that IOR is an intrinsic aspect of shifting attention and gaze direction and furthermore that it is not always advantageous to prevent return saccades.

Oculomotor inhibition of return in normal and mindless reading

“…Furthermore, no such evidence was found in the fine-grained analysis of fixation position focusing on letter position with a fixated word. These results are consistent with recent results from scene viewing and search suggesting that temporal O-IOR need not be accompanied by spatial O-IOR (Hooge et al, 2005;Smith & Henderson, 2009, 2011a. Although reading is a relatively young skill from the perspective of evolution, it appears to draw on much older systems developed for controlling the dynamic allocation of attention and eye movements.…”

“…In this way, O-IOR could facilitate eye movement control by helping observers avoid reinspecting recently fixated locations (Klein, 1988;Klein & MacInnes, 1999). Evidence concerning this hypothesis is currently mixed, with several reports of equal or greater refixation of previously fixated locations in visual search and scene viewing (Hooge et al, 2005;Smith & Henderson, 2009, 2011a, 2011b. In the present study, little evidence for spatial consequences of O-IOR on fixation probability was observed.…”

“…Oculomotor IOR (O-IOR) is an increase in saccade latencies when the eyes move back to a previously fixated location, as compared with a new control location (Klein & Hilchey, 2011). O-IOR, measured as an increase in fixation duration prior to a return saccade, has been reported in a variety of complex freeviewing tasks (Dodd, Van der Stigchel & Hollingworth, 2009;Farrell, Ludwig, Ellis & Gilchrist, 2010;Hooge & Frens, 2000;Hooge, Over, van Wezel & Frens, 2005;Klein & MacInnes, 1999;MacInnes & Klein, 2003;Ludwig, Farrell, Ellis & Gilchrist, 2009;Smith & Henderson, 2009, 2011aThomas et al, 2006).…”

Does oculomotor inhibition of return influence fixation probability during scene search?

“…Overt return of attention via eye movements has also been shown to experience delay (Klein & Hilchey 2011). Oculomotor IOR is thought to delay the programming of saccades to the previous fixation location (one back; Hooge, Over, van Wezel & Frens, 2005;Klein & MacInnes, 1999;MacInnes & Klein, 2003; and to the penultimate fixation location (two back; Dodd, Van der Stigchel & Hollingworth, 2009;Klein & MacInnes, 1999), and may even extend as far back as four fixations (four back; Dodd et al, 2009).…”

Inhibition of return functions within but not across searches

“…A number of groups have questioned whether IOR is functional in influencing return probability during visual search (e.g., Hooge, Over, vanWenzel, & Frens, 2005;Smith & Henderson, 2009), while others have produced evidence for its effect in search and suggested that it may have an influence on up to the five most recently inspected items (Snyder & Kingstone, 2000), and that these effects may be graded, with the most recently fixated items having more inhibition (Boot, McCarley, Kramer, & Peterson, 2004). Wang, Zhang, and Klein (2010) suggested that IOR operates in static or slower dynamic search, whereas they did not observe it in faster, dynamic search.…”