Contributions of visible persistence and perceptual set to the flash-lag effect: Focusing on flash onset abolishes the illusion

Abstract

Among other theories, visible persistence has been suggested to explain the flash-lag effect (FLE). According to this account, the flash is not compared to the moving object at its perceived onset, but at a later time while it is still subjectively visible. Therefore, it is reported to lag the moving object. We show that observers' perceptual set determines whether the persisting image of the flash or its onset is used to judge relative position. Spontaneously, observers use the persisting image, such that a flash-lag results. When forced to focus on the onset of the flash because flashes and stationary onset-only stimuli are mixed, observers base their judgments on the onset and the FLE is abolished. We found that perceptual set affected the FLE in the flash-initiated and in the continuous-motion paradigm. Finally, we showed that the position of the moving object was perceived without any blur and that the flash persisted subjectively for at least 60-80ms. Changes of perceptual set and visible persistence may underlie many of the previously reported modulations of the FLE.

The flash-lag effect and related mislocalizations: Findings, properties, and theories.

“…Linares and López-Moliner suggested a flash-lag effect did not occur; more specifically, they suggested that local spatial relationships between moving targets and flashed objects were preserved if those differences are used to detect global shape.^ The lack of a flash-lag effect if participants did not engage in judgment of position is consistent with the view that high-level processes contribute to the flash-lag effect; if the flash-lag effect resulted solely from low-level processes, it would have occurred regardless of participant intent (cf. Gauch & Kerzel, 2009).…”

“…The flash-lag effect does not occur before perceptual grouping (Watanabe, 2004; Watanabe et al, 2001) or pattern recognition (Linares & López-Moliner, 2007), and this suggests the flash-lag effect results from relatively high-level processes. Influences of conceptual knowledge (Nagai et al, 2010; Noguchi & Kakigi, 2008), beliefs regarding control of the target (Ichikawa & Masakura, 2006, 2010), predictability of the flashed object (Baldo & Namba, 2002; Vreven & Verghese, 2005), and perceptual set (Gauch & Kerzel, 2009) also suggest high-level processes contribute to the flash-lag effect. Nieman et al (2006) reported a flash-lag effect in the absence of luminance boundaries (with random dot stereograms), and this would require cortical processes sensitive to binocular disparities and be consistent with high-level processes.…”

“…Thus, visual persistence of a flashed object would last longer than visual persistence of a moving target (Efron, 1970; Hogben & Di Lollo, 1974), and this could result in a flashed object appearing to lag a moving target (Walker & Irion, 1982). Gauch and Kerzel (2009) suggested visual persistence, in conjunction with perceptual set, could account for most instances of the flash-lag effect. Whitney, Murakami, and Cavanagh (2000) presented a mask at the position of the flashed object immediately after the flashed object was presented.…”

“…Perceptual set. Gauch and Kerzel (2009) suggested participants respond differently if they are certain a flashed object will be presented than if they are uncertain whether a flashed object will be presented. Gauch and Kerzel presented a moving target accompanied by a flashed object or by a stationary object that was visible until the end of target motion.…”

Spatial mislocalization as a consequence of sequential coding of stimuli

“…Previous studies have indicated that such differences can contribute to spatial misperceptions, such as the flash-lag effect (cf. Gauch & Kerzel, 2009;Sheth, Nijhawan, & Shimojo, 2000;Whitney, Murakami, & Cavanagh, 2000). In fact, we accidentally confirmed one of these perceptual factors, eccentricity, as an additional contributor to the percept in the "code the rotating stimulus first" conditions of Experiment 3 (e.g., Baldo et al, 2002;Kirschfeld & Kammer, 1999).…”