Accuracy and Precision of Spatial Localization With and Without Saccadic Eye Movements: A Test of Two-Process Model

Abstract

and Sachio NAKAMIZO 1) 1) Kyushu University, JapanWe tested the two-process model of spatial localization (Adam, Ketelaars, Kingma, & Hoek, 1993) by measuring accuracy and precision of localization performance in three stimulus conditions: (i) no-saccade -observers were to maintain gaze on the fixation mark while target appeared for 1 s, (ii) saccade to on-target -they had to quickly saccade to and fixate on target remaining on for 1 s, and (iii) saccade to offtarget -they had to quickly saccade to the target appeared for 150 ms. Observers' task was to adjust position of a mouse cursor manually so that its position corresponds to the perceived position of the target. Results with six observers are consistent with the model suggesting localization performance to be mediated by memory-guided saccade for brief target and visually guided saccade for long duration target. The results further suggest that the memory-guided saccade provides relatively less accurate and precise information for localization and is a function of target eccentricity.Key words: spatial localization, two-process model, memory-guided saccade, visually guided saccade Adam, Ketelaars, Kingma, and Hoek (1993) reported on the time course and accuracy of spatial localization in which they demonstrated that localization performance showed an initial steep rise during the first 50 ms of stimulus duration followed by a gradual rise after 50 ms, reaching maximal performance at about 300 ms. They interpreted these two localization performance functions by the two-process model, which states that the two systems, namely the attention system for the initial steep rise and the eye movement system for the subsequent gradual rise, operate sequentially.The two process-model was supported by Adam et al. (1993) in which localization

Evidence for attentional processing in spatial localization

“…Specifically, we focus on the impact of identifying a number of digits at fixation on the localization performance of a peripheral target. We will first outline the two-process model of object localization proposed and investigated by Adam, Huys, van Loon, Kingma, & Paas ( 2000 ), Adam et al ( 1993 ); Adam, Paas, Ekering, & van Loon ( 1995 ) (see also Uddin, Ninose, & Nakamizo, 2004 ). We then present an experiment, using a dual-task method, that supports the assertion that visual attention is critical in localizing objects within the first 100 ms.…”

Differential roles of distracters in reflexive and memory-based localization

“…All observers were extensively experienced in psychophysical experiments and TY, TK, and DK were adept in recording eye movements. TY, TK, UK, and DK also participated in a previous experiment conducted by UK (Uddin et al, 2004) in which they were instructed to maintain a fixed gaze while stimuli were presented; eye movement data showed that they performed the tasks successfully.…”

“…Scanning of an object's location in a short period is inaccurate, and it usually takes a prolonged time to comprehend the exact location (Atkinson and Braddick, 1988). In addition to temporal factors, cognitive factors such as attention and eye movements play critical roles in localization (Adam et al, 1993;Tsal and Bareket, 1999;Uddin et al, 2004). The accuracy in manual localization is lower when attention alone is involved in encoding the target location compared to when attention followed by saccadic eye movements is involved (Adam et al, 1993;Uddin et al, 2004).…”

“…In addition to temporal factors, cognitive factors such as attention and eye movements play critical roles in localization (Adam et al, 1993;Tsal and Bareket, 1999;Uddin et al, 2004). The accuracy in manual localization is lower when attention alone is involved in encoding the target location compared to when attention followed by saccadic eye movements is involved (Adam et al, 1993;Uddin et al, 2004). Moreover, with the increase in exposure durations, accuracy remains almost constantly impaired in the former condition but dramatically improves in the latter condition (Adam et al, 1993(Adam et al, , 1995.…”

Egocentric Dynamic Planar Organization of the Angular Movements of the Arm During a Violinist’s Performance of a Mozart Symphony

“…Where studies have been made with wide visual angles or in the far peripheral visual field, the conclusions have been mixed. Different studies reported both the tendency to overestimate (Mateeff and Gourevich 1983;Hubbard and Ruppel 2000;Uddin 2006;Fortenbaugh and Robertson 2011) or underestimate (Bock 1993;Bruno and Morrone 2007;Enright 1995) the eccentricity of static targets in visual space, as well as the tendency to overestimate (Bedell and Johnson 1984) or underestimate (Newsome 1972;Schneider et al 1978) size of stimuli presented in peripheral visual field. The fact that experimental inconsistencies arise so frequently may reflect the complexity of the psychological and perceptual processes involved in the apparently simple tasks of locating objects in the visual field and defining their size and shape.…”