Alon Zivony

The role of search difficulty in intertrial feature priming

Previous research has shown that intertrial repetition of target and distractors task-relevant properties speeds visual search performance, an effect known as priming of pop-out (PoP). Recent accounts suggest that such priming results, at least in part, from a mechanism that speeds post-selectional, response-related processes, the marker of which is an interaction between repetition of the target and distractor features and repetition of the response from the previous trial. However, this response-based component of inter-trial priming has been elusive, and it remains unclear what its boundary conditions might be. In addition, what information is represented in the episodic memory traces that underlie the response-based component has not yet been characterized. Here, we show that the response-based component of feature priming reflects an episodic memory retrieval mechanism that is not mandatory or automatic but may be described as a heuristic that subjects sometimes use, in particular when the overall difficulty of the search task is high. In addition, we show that the conjunction of the target and distractor features forms the context that is reactivated during episodic retrieval. Finally, we show that target-distractor discriminability is an important modulator of the selection-based component. The findings are discussed within the framework of the dual-stage model of inter-trial priming (Lamy, Yashar, & Ruderman, 2010).

Attentional sets influence perceptual load effects, but not dilution effects

Perceptual load theory [Lavie, N. (1995). Perceptual load as a necessary condition for selective attention. Journal of Experimental Psychology: Human Perception and Performance, 21, 451–468.; Lavie, N., & Tsal, Y. (1994) Perceptual load as a major determinant of the locus of selection in visual attention. Perception & Psychophysics, 56, 183–197.] proposes that interference from distractors can only be avoided in situations of high perceptual load. This theory has been supported by blocked design manipulations separating low load (when the target appears alone) and high load (when the target is embedded among neutral letters). Tsal and Benoni [(2010a). Diluting the burden of load: Perceptual load effects are simply dilution effects. Journal of Experimental Psychology: Human Perception and Performance, 36, 1645–1656.; Benoni, H., & Tsal, Y. (2010). Where have we gone wrong? Perceptual load does not affect selective attention. Vision Research, 50, 1292–1298.] have recently shown that these manipulations confound perceptual load with “dilution” (the mere presence of additional heterogeneous items in high-load situations). Theeuwes, Kramer, and Belopolsky [(2004). Attentional set interacts with perceptual load in visual search. Psychonomic Bulletin & Review, 11, 697–702.] independently questioned load theory by suggesting that attentional sets might also affect distractor interference. When high load and low load were intermixed, and participants could not prepare for the presentation that followed, both the low-load and high-load trials showed distractor interference. This result may also challenge the dilution account, which proposes a stimulus-driven mechanism. In the current study, we presented subjects with both fixed and mixed blocks, including a mix of dilution trials with low-load trials and with high-load trials. We thus separated the effect of dilution from load and tested the influence of attentional sets on each component. The results revealed that whereas perceptual load effects are influenced by attentional sets, the dilution component is not. This strengthens the notion that dilution is a stimulus-driven mechanism, which enables effective selectivity.

Attentional engagement is not sufficient to prevent spatial capture

What conditions, if any, can fully prevent attentional capture (i.e., involuntary allocation of spatial attention to an irrelevant object) has been a matter of debate. In a previous study, Folk, Ester, and Troemel (Psychonomic Bulletin & Review 16:127–132, 2009) suggested that attentional capture can be blocked entirely when attention is already engaged in a different object. This conclusion relied on the finding that in a search for a known-color target in a rapid serial visual presentation stream, a peripheral distractor with the target color did not further impair target identification performance when a distractor also with the target color that appeared in the stream had already captured attention. In the present study, we argue that this conclusion is unwarranted, because the effects of the central and peripheral distractors could not be disentangled. In order to isolate the effect of the peripheral distractor, we introduced a distractor–target letter compatibility manipulation. Our results showed that the peripheral distractor summoned attention, irrespective of whether attention had just been engaged. We conclude that neither spatially focused attention nor attentional engagement is sufficient to prevent attentional capture.

Contingent capture is weakened in search for multiple features from different dimensions.

Can observers maintain more than 1 attentional set and search for 2 features in parallel? Previous studies that relied on attentional capture by irrelevant distractors to answer this question focused on features from the same dimension and specifically, on color. They showed that 2 separate color templates can guide attention selectively and simultaneously. Here, the authors investigated attentional guidance by 2 features from different dimensions. In three spatial-cueing experiments, they compared contingent capture during single-set versus dual-set search. The results showed that attention was guided less efficiently by 2 features than by just 1. This impairment varied considerably across target-feature dimensions (color, size, shape and orientation). Confronted with previous studies, our findings suggest avenues for future research to determine whether impaired attentional guidance by multiple templates occurs only in cross-dimensional disjunctive search or also in within-dimension search. The present findings also showed that although performance improved when the target feature repeated on successive trials, a relevant-feature cue did not capture attention to a larger extent when its feature matched that of the previous target. These findings suggest that selection history cannot account for contingent capture and affects processes subsequent to target selection.

Target activation and distractor inhibition underlie priming of pop-out: A response to Dent (this issue)

ABSTRACT Visual search is faster when the target and distractors features repeat than when they switch on successive trials, a phenomenon known as priming of pop‐out (PoP). In previous work, we suggested that two mechanisms, each indexed by a repetition benefit and a switch cost underlie PoP: target activation and distractor inhibition. Consistent with this account, we reported strong correlations between the benefit and cost indexing each mechanism and concluded that there are stable individual differences on target‐activation and distractor‐inhibition processes. In subsequent work, we noted flaws in our baseline for benefits and costs and suggested a different baseline. Yet, we did not explore the implications of these flaws for our previous conclusions ‐ a gap that Dent (this issue) filled in a large‐scale replication of our study. He found our reported correlations to entirely vanish when the corrected baselines are used, whereas repetition benefits were correlated and so were switching costs. He concluded that his findings invalidate the activation‐inhibition account of PoP and proposed a hybrid account, according to which repetition effects reflect activation and inhibition, whereas switch costs index a conflict‐resolution process. Here, we claim that failure to observe correlations between indices of the same components invalidates the claim that there are stable individual differences on these components but does not challenge the idea that target‐activation and distractor inhibition underlie PoP. We reanalyzed the data from four published experiments. As Dent (this issue), we find no correlations between indices of the same component. However, we show that novel predictions of the activation‐inhibition components account are supported, whereas the predictions of the conflict‐resolution account are disconfirmed.

Contingent Attentional Engagement: Stimulus- and Goal-Driven Capture Have Qualitatively Different Consequences

We examined whether shifting attention to a location necessarily entails extracting the features at that location, a process referred to as attentional engagement. In three spatial-cuing experiments (N = 60), we found that an onset cue captured attention both when it shared the target’s color and when it did not. Yet the effects of the match between the response associated with the cued object’s identity and the response associated with the target (compatibility effects), which are diagnostic of attentional engagement, were observed only with relevant-color onset cues. These findings demonstrate that stimulus- and goal-driven capture have qualitatively different consequences: Before attention is reoriented to the target, it is engaged to the location of the critical distractor following goal-driven capture but not stimulus-driven capture. The reported dissociation between attentional shifts and attentional engagement suggests that attention is best described as a camera: One can align its zoom lens without pressing the shutter button.

Stereotype Deduction About Bisexual Women

Bisexuals are an invisible sexual minority. However, at the same time, bisexuals are stereotypically associated with confusion and promiscuity. Stereotype learning theories suggest that individuals who are unfamiliar with a social group are less likely to have stereotypical beliefs about its members. In contrast, it has been recently hypothesized that stereotypes about bisexuality are not necessarily learned but rather deduced based on common conceptualizations of sexuality. Because stereotypes are suppressed only if they are recognized as offensive, lack of knowledge regarding bisexual stereotypes should actually enhance their adoption. To assess the strength of the two competing accounts, we examined the relationship between explicit knowledge of bisexual stereotypes and stereotypical evaluation of bisexual individuals. Heterosexual participants (N = 261) read a description of two characters on a date and evaluated one of them. Bisexual women were evaluated as more confused and promiscuous relative to nonbisexual women. Moreover, the stereotypical evaluations of bisexual women were inversely related to knowledge about these stereotypes. The findings support the notion that bisexual stereotypes are not learned but rather deduced from shared assumptions about sexuality. Consequently, public invisibility not only exists alongside bisexual stereotypes but might also exacerbate their uninhibited adoption.

Perceptual Processing is Not Spared During the Attentional Blink

Identification of the second of two targets is impaired when these appear within 500 ms of each other. This phenomenon, known as the attentional blink (AB) is thought to reflect disrupted post-perceptual processing. Yet, decisive empirical support for this claim is lacking. We measured the depth of the AB, while manipulating the second target’s reporting feature. We reasoned that if perceptual processing is unaffected by the blink, all the features of the blinked target should have equal access to working memory. In contrast with this prediction, we found identity and semantic-category reports to be more severely impaired by the blink than color reports, although baseline performance was similar in the two report conditions. These findings suggest that high-level features are more poorly represented in working memory than low-level features during the blink. We conclude that the attentional blink disrupts perceptual processing. Implications for contemporary models of the attentional blink are discussed.

There and back again: Revisiting the on-time effect

In apparent motion, static stimuli presented successively in shifted locations produce a subjective percept of continuous motion. Reducing stimulus exposure (or on-time) was shown to consistently increase the perceived velocity of apparent motion (Vision Research 29 (1989), 335-347), yet surprisingly little investigation has followed up on the discovery of this illusion. In five experiments, we delineate the boundary conditions of the on-time illusion in order to clarify its underlying mechanisms. Subjects viewed multi-item apparent-motion displays, in which at some point, on-time duration either increased or decreased. Objective velocity remained unchanged, yet participants had to judge whether they perceived the motion to become slower or faster. We observed the on-time illusion during both fast and slow apparent motion. The effect was not modulated by stimulus luminance, thus precluding an energy-summation account of the illusion. It generalized from speed perception to time perception in a temporal bisection task. The illusion was specific to apparent motion, as it did not occur with veridical motion. Finally, the illusion persisted when on-time and off-time were not confounded, that is, when off-time remained constant. These findings are discussed in the framework of current models of motion perception.

Dissociation between Attentional Capture and Attentional Engagement: an Attentional Blink study

Our ability to attend to successive events is severely limited: observers often fail to report the second of two targets that appear within 200-500ms from each other, a phenomenon known as the attentional blink. Here, we examined what processes are disrupted during the blink. Specifically, we examined whether the blink affects (1) the ability of a distractor that matches the attentional set to capture attention and initiate an attentional episode and (2) attentional engagement in this distractor, that is, the extraction of its response-relevant features. We found that attentional capture occurs irrespective of whether the attention-grabbing distractor occurs during or outside the blink, but that attention is engaged in the object that immediately follows this distractor in time. Taken together, these findings strongly support the Delayed Engagement Account of the attentional blink as well as demonstrate that attentional capture and attentional engagement can be dissociated. Meeting abstract presented at VSS 2015.