Expectations About the Temporal Structure of the World Result in the Attentional Blink and Repetition Blindnsess

Expectations About the Temporal Structure of the World Result in the Attentional Blink and Repetition Blindness Cory A. Rieth & Edward Vul (crieth, evul@ucsd.edu) Department of Psychology, 9500 Gilman Dr. # 109 La Jolla, CA 92093-109 USA Abstract and memory (Bowman & Wyble, 2007; Olivers & Meeter, Here we do not aim to supplant these models, but only to provide a rational account of these dynamics, to explain why the visual system may exhibit AB and RB. We remain agnos- tic to the particular processes and implementations, and in- stead seek an understanding of the computational principles that may be in play. We develop a probabilistic model of tar- get identification by co-occurrence detection, which aims to infer which item occurred simultaneously with the cue, given temporal uncertainty and expectations about world dynam- ics. First we describe the derivation of the model based on assumed temporal statistics, then illustrate its application to the basic RB and AB paradigms. Finally, we will apply this model to AB response distributions. We consider how repetition blindness and the attentional blink might arise from prior assumptions about the occurrence of task-relevant states of the world. Repetition blindness and the attentional blink are behavioral deficits in the identification of items during rapid serial visual presentation at varying delays after identifying the first “target.” Here we propose that both of these effects are explained by rational inference given prior expectations about the timing of task-relevant world transi- tions. While such expectations would be helpful in the natural world, they may result in unanticipated biases in laboratory settings. We show that a rational model using prior expecta- tions of the timing of task-relevant information captures the basic repetition blindness and the attentional blink effects, and also the specific distributions of errors made during the atten- tional blink. Keywords: Attentional blink; Repetition blindness; Attention; Computational Modeling; Bayesian Models Introduction Attentional Blink! Repetition blindness and the attentional blink refer to com- mon failures in identifying stimuli shortly after an important event. Both phenomena are typically studied in rapid serial visual presentation (RSVP) tasks, in which many stimuli (of- ten letters or digits) are displayed in quick succession. In the task people are asked to pick out some specific “targets” from the RSVP stream (for instance, letters among digits, or letters cued by a ring). After the first target (T 1 ), a second target (T 2 ) appearing within a few stimuli of the first tends to be misreported – this is called the “attentional blink” (AB; Fig- ure 1, top; Raymond, Shapiro, & Arnell, 1992; Weichselgar- tner, 1987). If an identical target is presented twice without much time intervening, people tend to not notice the repeti- tion, yielding “repetition blindness” (RB; e.g., the ‘E’ in the bottom section of Figure 1; Kanwisher, 1987). Although both RB and AB have many surface similarities, they follow a qualitatively different time-course as a function of the “stimulus onset asynchrony” (or lag) – the time be- tween the onset of T 1 and the onset of T 2 . The attentional blink exhibits lag-one sparing – if T 2 appears immediately after T 1 , detection is often not impaired; in contrast, the RB deficit is most pronounced at such short delays. Moreover, when manipulated within one experiment, these effects have independent, dissociable effects (Chun, 1997). Several ac- counts of RB and AB postulate resource limitations (Shapiro, Raymond, & Arnell, 1997) in individuating items into unique tokens and binding them to type identities (Kanwisher, 1987; Bowman & Wyble, 2007). Moreover, the time-course of these effects has been the target of several computational process models that utilize specific mechanistic dynamics of attention I! E! C! F! K! O! G! M! D! J! B! L! H! N! A! P! ✔! I! E! C! F! K! O! G! M! D! J! B! L! H! N! A! P! ✗! I! E! C! F! K! O! G! M! D! J! B! L! H! N! A! P! ✗! I! E! C! F! K! O! G! M! D! J! B! L! H! N! A! P! ✔! Repetition Blindness! I! E! E! F! K! O! G! M! D! J! B! L! H! N! A! P! ✗! I! E! F! E! K! O! G! M! D! J! B! L! H! N! A! P! ✗! I! E! F! K! O! E! G! M! D! J! B! L! H! N! A! P! ✔! time ! Figure 1: Repetition blindness and attentional blink paradigms. Each row of letters represents a particular type of trial where the letters appear in rapid succession. Repetition blindness arises when a target repeats, and participants indicate whether it appeared once or twice: performance is worse at short inter-target intervals when the two targets are identical compared to when they are different. The attentional blink occurs when the task requires identifying two designated targets: Participants are can report items in quick succes- sion, as in the top attentional blink row (“lag-one sparing”); how- ever, when the second target appears a few items later, participants are less accurate. RSVP Identification Model We assume that people identify targets in an RSVP task via the probability that a given item co-occurred with the cue. Under this assumption, the observer’s task is to infer the let- ter identity ( L ) of the second target (T 2 ), by marginalizing over all possible stimuli used in the experiment (x i ) that may have coincided with the cue. The probability that the cue