Modulation of the perception of temporal order by attentional and pre-attentional factors

Abstract

When two stimuli are presented simultaneously to an observer, the perceived temporal order does not always correspond to the actual one. In three experiments we examined how the location and spatial predictability of visual stimuli modulate the perception of temporal order. Thirty-two participants had to report the temporal order of appearance of two visual stimuli. In Experiment 1, both stimuli were presented at the same eccentricity and no perceptual asynchrony between them was found. In Experiment 2, one stimulus was presented close to the fixation point and the other, peripheral, stimulus was presented in separate blocks in two eccentricities (4.8º and 9.6º). We found that the peripheral stimulus was perceived to be delayed in relation to the central one, with no significant difference between the delays obtained in the two eccentricities. In Experiment 3, using three eccentricities (2.5º, 7.3º and 12.1º) for the presentation of the peripheral stimulus, we compared a condition in which its location was highly predictable with two other conditions in which its location was progressively less predictable. Here, the perception of the peripheral stimulus was also delayed in relation to the central one, with this delay depending on both the eccentricity and predictability of the stimulus. We argue that attentional deployment, manipulated by the spatial predictability of the stimulus, seems to play an important role in the temporal order perception of visual stimuli. Yet, under whichever condition of spatial predictability, basic sensory and attentional processes are unavoidably entangled and both factors must concur to the perception of temporal order. Key wordsThe judgment of temporal order of a pair of closely timed stimuli is a very old and still unsolved problem (1) that has been attracting the attention of many neurophysiologists and psychologists. When two stimuli are presented to an observer simultaneously or nearly simultaneously, the perceived order does not always correspond to the actual one. Several models of temporal order judgment have been proposed in the last decades to account for the source of judgment errors (2-5). These models assume that temporal order perception depends on the time when sensory information reaches a central comparator. In the visual system this depends on the transmission latencies of the sensory signals from the retina to the putative central comparator. Indeed, physiological proper-

Aging and Parkinson's disease as functional models of temporal order perception

“…Results support the idea proposed by Stelmach and Herdman (1991), Haddad, Carreiro, and Baldo (2002), and Baldo, Cravo, and Haddad (2007) that attention plays an important role in the perception of the temporal order of visual stimuli. By directing attention to the region of the visual field where one of the stimuli will appear, the participant anticipates the sensory processing of that stimulus relatively to the processing of the other stimulus that will appear in a non-attended region.…”

“…We note that we have just considered the results of Experiment 2 as reflecting the effect of attention on the perception of temporal order, which is supported by previous studies (Stelmach & Herdman, 1991;Haddad et al, 2002;Baldo et al, 2007). Indeed, participants were instructed to pay attention to the side of the screen pointed to by the cue and that was the only significant difference between the examined conditions.…”

The Time of Perception and the Other Way Around

“…The idea behind TOJ manipulation is that one stimulus of the pair could receive some kind of perceptual priority that would alter the time it takes to reach awareness. The factors that establish this perceptual priority could be grouped into pre-attentive and attentive processes (Haddad, Carreiro, & Baldo, 2002). Pre-attentive, or sensory, factors comprise some basic features of the sensory stimulus, such as its physical intensity or visual eccentricity (Haddad, Klein, & Baldo, 1999).…”

Perceived onset time and position of a moving stimulus

“…One of the easiest ways to manipulate attention is to change instructions or present valid cues in the FLE and FE experiments (e.g., Kirschfeld & Kammer, 2000). Baldo with colleagues , Haddad, Carreiro, & Baldo, 2002) has explicitly tested the role of attention in the FLE and showed that the result depends very much on the task. The magnitude of the FLE increased with the decreased predictability of the flashesÕ eccentricity or position.…”

“…Comparable results come also from . In another study from Baldo and his colleagues (Haddad et al, 2002), the effect of attention was separated from the effect of the eccentricity of the peripheral flash. Presenting the flashes at different eccentricity in separate blocks (4.8°and 9.6°or 2.5°, 7.3°and 12.1°) abolished the effect of the eccentricity that was revealed in conditions where the flashÕs distance from the central dot varied randomly from trial-to-trial.…”