Temporal target integration underlies performance at lag 1 in the attentional blink.

Abstract

When two targets follow each other directly in rapid serial visual presentation (RSVP), they are often identified correctly but reported in the wrong order. These order reversals are commonly explained in terms of the rate at which the two targets are processed, the idea being that the second target can sometimes overtake the first in the race toward conscious awareness. The present study examined whether some of these order reversals might alternatively be due to a mechanism of temporal integration whereby targets appearing closely in time may be merged into a single representation. To test this integration account, we used an attentional blink task in which the two targets could be combined perceptually in a meaningful way such that the conjunction of the two target elements constituted a possible target stimulus itself. The results showed that when targets appeared at Lag 1, observers frequently reported seeing only a single merged target stimulus, and these reports occurred up to approximately three times as often as (real) order reversals. When the possibility to report the integrated percept was removed, order reversals consequently tripled. These results suggest that integration may actually be the primary cause of order reversals in dual-target RSVP tasks.

Supplementation of gamma-aminobutyric acid (GABA) affects temporal, but not spatial visual attention

“…There was no main effect of GABA, and no interaction with lag (F's < 1). Lag by itself had a pronounced effect, as is commonly observed in this version of the task (e.g., Akyürek et al, 2012), F(1.1, 26) = 217.08, MSE = 0.03, p < .001, η p 2 = 0.9: At Lag 1, accuracy was much lower (30.5%) than at Lag 3 (74.3%) and Lag 8 (81.4%). Conditional T2 accuracy (T2|T1) is shown in the top right panel of Fig.…”

“…This phenomenon may in turn be related to a loss of order information that is most prevalent in the Lag 1 condition, suggesting that the typical increase in identification performance may come at a cost (Hommel & Akyürek, 2005). Akyürek et al (2012) provided proof that these performance characteristics at Lag 1 are related to the occurrence of temporal integration, a perceptual process by which the successive targets are combined into a single, integrated percept. Thus, next to providing an index of temporal attention and the AB, the RSVP task can also be used to assess temporal integration.…”

“…This sample size was chosen to match those of previous studies that were conducted with the same tasks (Akyürek & Schubö, 2011;Akyürek et al, 2012). The study was conducted in accordance with the Declaration of Helsinki (2008), and approved by the departmental ethical committee prior to its execution (15078-NE).…”

“…A secondary aspect that has been studied with RSVP is temporal integration, which can be observed when targets succeed each other directly, without intervening distractors, at Lag 1 (Akyürek et al, 2012). Lag 1 is a special case in RSVP, because many studies report Lag 1 "sparing", a paradoxical improvement of target identification in the shortest Lag condition, where processing time is most limited (Visser, Bischof, & Di Lollo, 1999).…”

“…A light gray (RGB 192,192,192) background was maintained throughout the experiment. Stimuli were adopted from Akyürek et al (2012). Before the start of each trial a fixation cross ("+"), drawn in 18-point, boldface Courier New font appeared at the center of the screen.…”