Guided Search 3.0

TAM: Explaining off-object fixations and central fixation tendencies as effects of population averaging during search

“…Figure 3a shows these off-object fixations for one of the Purkinje observers. The 541 behaviors illustrated in this figure cannot be explained by any theory of visual search proposing direct movements of gaze from one proto-object to another (Ehinger et al, 2009; Itti & Koch, 2000; Kanan et al, 2009; Wolfe & Gancarz, 1996). This is because these theories assume no competition between proto-objects after their rank ordering for selection—the top-ranked object is always selected (not the top two, three, etc.…”

“…Indeed, in all cases in which an eye movement is made before pruning has isolated the hotspot, population averaging will likely prevent gaze from landing directly on an object; despite TAM wanting to look at proto-object h (the hotspot), target map activity from proto-objects x , y , and z would pull gaze away from this desired target. In contrast, search theories that do not use a population code predict that gaze should move serially from one proto-object to the next (e.g., Ehinger, Hidalgo-Sotelo, Torralba, & Oliva, 2009; Itti & Koch, 2000; Kanan, Tong, Zhang, & Cottrell, 2009; Wolfe & Gancarz, 1996), with their order of fixation determined by how the patterns were prioritized by preattentive processes. These theories predict relatively accurate eye movements to objects and few off-object fixations.…”

A theory of eye movements during target acquisition.

“…The potential for eye movements to inform search theory has not gone unnoticed, with several predominantly covert theories of search also making implicit (Itti & Koch, 2000; Koch & Ullman, 1985; Olshausen, Anderson, & van Essen, 1993; Wolfe, 1994), and occasionally explicit (Tsotsos et al, 1995; Wolfe & Gancarz, 1996) claims that overt eye movement behavior will follow naturally from hypothesized covert search dynamics. Although few theoretical treatments have systematically compared simulated search behavior to human eye movements (see Rao, Zelinsky, Hayhoe, & Ballard, 1996, 2002, and Navalpakkam & Itti, 2005, for exceptions), there is good reason why this should become common practice.…”

“… 17 Note that Wolfe and Gancarz, 1996 outlined an updated 3.0 version of GSM that included retina preprocessing. However, this model was not fully implemented and lacked the computational detail and thorough behavioral testing included with the 2.0 version.…”

Using Eye Movements to Understand how Security Screeners Search for Threats in X-Ray Baggage

“…Despite their differences, the models of search share the common idea that, during the search, our limited resources need to be directed to given objects in order to determine whether those objects are targets [13]. In the classic Guided Search model, which has been revised several times since its inception [8,14,15,16], attention is directed towards target-similar objects, one at a time, until a target is found, or until the searcher decides to quit. The decision to terminate search can depend on a number of factors, including the time spent searching and errors made on previous trials [17].…”