Attention and the Speed of Information Processing: Posterior Entry for Unattended Stimuli Instead of Prior Entry for Attended Stimuli

Abstract

Why are nearly simultaneous stimuli frequently perceived in reversed order? The origin of errors in temporal judgments is a question older than experimental psychology itself. One of the earliest suspects is attention. According to the concept of prior entry, attention accelerates attended stimuli; thus they have “prior entry” to perceptive processing stages, including consciousness. Although latency advantages for attended stimuli have been revealed in psychophysical studies many times, these measures (e.g. temporal order judgments, simultaneity judgments) cannot test the prior-entry hypothesis completely. Since they assess latency differences between an attended and an unattended stimulus, they cannot distinguish between faster processing of attended stimuli and slower processing of unattended stimuli. Therefore, we present a novel paradigm providing separate estimates for processing advantages respectively disadvantages of attended and unattended stimuli. We found that deceleration of unattended stimuli contributes more strongly to the prior-entry illusion than acceleration of attended stimuli. Thus, in the temporal domain, attention fulfills its selective function primarily by deceleration of unattended stimuli. That means it is actually posterior entry, not prior entry which accounts for the largest part of the effect.

Does attention speed up processing? Decreases and increases of processing rates in visual prior entry

“…line with the results obtained by Weiß et al (2013), the only other study that directly addressed the same question.…”

“…The relative prior entry measured by the TVA-based method is about 26 ms with 16 ms caused by the slowdown of the unattended target being the larger contribution. That the decrease in processing rate of the unattended stimulus contributes more to prior entry than the increase in processing rate of the attended stimulus is in line with the results of Weiß et al (2013). Importantly, looking at the processing rates, the overall rate C appears to be conserved under the attentional manipulation.…”

“…Most intriguingly, the fundamental question of whether prior entry arises from attention-based speed benefits for the attended target or if the processing of the unattended is slowed down remained unasked until recently (Weiß, Hilkenmeier, & Scharlau, 2013). Most likely, it has been ignored for so long because TOJs, the prevailing method in prior-entry research, are completely indifferent to this difference.…”

“…One recent study directly addressed the role of deceleration in prior entry assessed by TOJs. Weiß et al (2013) coupled TOJs with an additional latency measure. They used two stylized clocks on which rotating hands appeared separated by a variable time interval.…”

“…Thus, it must be concluded that neither evidence from related phenomena, electrophysiological evidence, nor, finally, the study by Weiß et al (2013), the only one that has explicitly targeted this question so far, are able to provide compelling evidence for pure acceleration, pure deceleration, or combinations of both. In the present study, we set out to find an answer for this fundamental question using a method based on stimulus identification (Bundesen, 1990) that is not subject to the relativeness of TOJs.…”