Intertrial Priming Effects Research Articles

Building Bridges: Visual Search Meets Action Control via Inter-Trial Sequence Effects

What we have attended to in the past, as well as the stimulus context associated with past motor responses, have a strong impact on our current behavior. These influences have been investigated through inter-trial priming effects in visual search and sequence effects in action control, respectively. These two research fields are strongly complementary at the theoretical level and show striking similarities in their experimental-task structure, analyses, and results. Yet, they have developed largely separately. Here, we claim that such fragmentation impedes progress in these two research strands and highlight the potential benefits of intensifying crosstalk between visual search and action control in future research by exploiting the existing structural similarities with regard to sequence effects. We first discuss the main phenomena and theoretical explanations in each field, while emphasizing the similarities and differences between them. Then, we illustrate how the two fields could integrate each other’s insights—namely, how visual-search research could draw on the action-control literature to clarify the role of retrieval in selection and how action-control research could draw on the visual-search literature to explain response-related processes in more complex environments. We argue that combining the two research traditions is necessary for a coherent account of search-for-action behavior.

The long and the short of priming in visual search.

Memory affects visual search, as is particularly evident from findings that when target features are repeated from one trial to the next, selection is faster. Two views have emerged on the nature of the memory representations and mechanisms that cause these intertrial priming effects: independent feature weighting versus episodic retrieval of previous trials. Previous research has attempted to disentangle these views focusing on short term effects. Here, we illustrate that the episodic retrieval models make the unique prediction of long-term priming: biasing one target type will result in priming of this target type for a much longer time, well after the bias has disappeared. We demonstrate that such long-term priming is indeed found for the visual feature of color, but only in conjunction search and not in singleton search. Two follow-up experiments showed that it was the kind of search (conjunction versus singleton) and not the difficulty, that determined whether long-term priming occurred. Long term priming persisted unaltered for at least 200 trials, and could not be explained as the result of explicit strategy. We propose that episodic memory may affect search more consistently than previously thought, and that the mechanisms for intertrial priming may be qualitatively different for singleton and conjunction search. Electronic supplementary material The online version of this article (doi:10.3758/s13414-015-0860-2) contains supplementary material, which is available to authorized users.

Is goal-directed attentional guidance just intertrial priming? A review

According to most models of selective visual attention, our goals at any given moment and saliency in the visual field determine attentional priority. But selection is not carried out in isolation--we typically track objects through space and time. This is not well captured within the distinction between goal-directed and saliency-based attentional guidance. Recent studies have shown that selection is strongly facilitated when the characteristics of the objects to be attended and of those to be ignored remain constant between consecutive selections. These studies have generated the proposal that goal-directed or top-down effects are best understood as intertrial priming effects. Here, we provide a detailed overview and critical appraisal of the arguments, experimental strategies, and findings that have been used to promote this idea, along with a review of studies providing potential counterarguments. We divide this review according to different types of attentional control settings that observers are thought to adopt during visual search: feature-based settings, dimension-based settings, and singleton detection mode. We conclude that priming accounts for considerable portions of effects attributed to top-down guidance, but that top-down guidance can be independent of intertrial priming.

Visual consciousness and intertrial feature priming

Intertrial repetition priming plays a striking role in visual search. For instance, when searching for a target with a unique color, performance is substantially better when the specific color of the target repeats on successive trials (Maljkovic & Nakayama, 1994). Recent research has relied on objective measures of performance to show that priming improves the perceptual quality of the repeated target. Here, we examined the relation between priming and conscious perception of the target by adding a subjective measure of perception. We used backward masking to create liminal perception, that is, different levels of subjectively conscious perception of the target using exactly the same stimulus conditions. The displays in either probe trials (in which priming benefits are measured, experiment 1) or in prime trials (in which memory traces are laid down, experiment 2) were masked. The results showed that intertrial priming improves full access to awareness of the repeated target but only for targets that already achieved partial access to awareness. In addition, they show that full awareness of the target is necessary in both the prime and probe trials for intertrial priming effects to emerge. Implications for the role of implicit short-term memory in visual search are discussed.

Temporal position priming: Memory traces of recent experience bias the allocation of attention in time.

Explicit expectations can guide attention toward the time at which an upcoming target is likely to appear. However, in real-life situations, explicit preknowledge of upcoming events' temporal occurrence is rarely provided. We investigated whether implicit memory traces can guide attention in time, as they guide attention to recently attended features and locations (priming of pop-out and priming of location; V. Maljkovic & K. Nakayama, 1994, Priming of pop-out: I. Role of features, Memory & Cognition, Vol. 22, pp. 657-672; V. Maljkovic & K. Nakayama, 1996, Priming of pop-out: II. The role of position, Perception & Psychophysics, Vol. 58, pp. 977-991). Using a rapid serial visual presentation task, we show a temporal position priming (TPP) effect by which search performance is speeded when the target temporal position within the visual stream happens to repeat on consecutive trials. We show that such repetition priming is one of the mechanisms that underlie the much-studied sequential effect of the foreperiod. We further demonstrate that the learned association that gives rise to TPP does not require the selection or execution of a motor response and that it affects perceptual stages of visual processing. The relations between these findings and existing accounts of the sequential effect as well as with other intertrial priming effects in visual search are discussed.

Learning what to expect: context-specific control over intertrial priming effects in singleton search

The present study explored the degree to which repetition effects in color pop-out search from trial n - 1 to trial n are subject to the attentional control settings of the observer. Intertrial priming effects were compared between two contexts that differed in terms of the utility of immediate prior experience for current performance; in one context, the target was likely to repeat, and in the other context, the target was likely to alternate from one trial to the next. Across two experiments, priming of pop-out (PoP) effects (Malkjovic & Nakayama; Memory & Cognition 22:657-672, 1994) were modulated in accord with the probability of target color repetition in a given trial context. Importantly, this modulation persisted when trial history preceding trial n - 1 was controlled for. Furthermore, this control over PoP seems not to derive from explicit strategies and is not an artifact of randomly occurring strings of same-target trials. We argue that priming effects in singleton search from trial n - 1 to trial n are subject to a form of implicit top-down control.

Revisiting the time course of inter-trial feature priming in singleton search

Current theories of the locus of inter-trial priming effects in efficient visual search posit an early perceptual component that reflects the short-term influence of a memory trace for low-level stimulus attributes. Despite the fact that this memory trace is hypothesized to be short term, and should therefore have a diminishing influence on performance over time, there has been relatively little study of the effect of time alone on singleton priming effects. The present series of experiments addresses this issue by systematically examining the effect of time on the priming of pop-out (PoP) effect. In Experiment 1, we show that the PoP effect does indeed diminish with increases in the RSI between trials, and does so in accord with a power-law function. In Experiment 2, we show that temporal discriminability of trial n-1 from the trial that precedes it does not contribute to PoP effects. The results of Experiment 3 revealed two key results: (1) the PoP effect survives an equivalent number of intervening trials across very different RSI conditions; and (2) the cumulative target repetition benefit does depend on the RSI between trials. Together, the results favor neither a simple passive decay nor a strong episodic retrieval account of the PoP effect.

Dimension-specific intertrial priming effects are task-specific: Evidence for multiple weighting systems.

Feature singleton search is faster when the target-defining dimension repeats across consecutive trials than when it changes (Found & Müller, 1996). However, this dimension repetition benefit (DRB) has also been demonstrated for the tasks with no search component (Mortier, Theeuwes, & Starreveld, 2005). If DRBs in the search and non-search tasks have the same origin, significant DRBs across trials of different tasks should rise. Two different tasks varied either in a predictable manner (Experiment 1) or randomly (Experiment 2) across trials. In detection task, search displays containing either color or orientation singletons were used. Discrimination task required identification of either color or orientation of a single presented item (non-search display). In Experiment 3, participants performed only the discrimination task, while the search and non-search displays varied randomly. There were significant DRBs for both tasks when the task repeated but not when the task changed (Experiments 1 and 2). DRBs were significant both when the display type repeated and when it changed (Experiment 3). Overall, the findings can be well explained by assuming multiple, independent dimension-weighting systems generating DRBs in different tasks.

A dual-stage account of inter-trial priming effects

The study of inter-trial effects in visual search has generated an increasing amount of research in recent years. However, the mechanisms underlying these effects are still a matter of debate. Two rival accounts have been suggested. One view stipulates that inter-trial effects facilitate early perceptual/attentional processes, whereas the other proposes that it affects post-perceptual response-related processes. Here, we focused on the priming of pop-out effect (PoP, Maljkovic & Nakayama, 1994), which refers to the well-established finding that performance on singleton search is faster when the target and distractors features repeat on two consecutive trials than when they switch. We set out to resolve the current controversy surrounding PoP by suggesting a dual-stage account, according to which PoP speeds both an early perceptual stage and a later, response-related stage of visual search. We were able to dissociate the hypothesized components of PoP by tracking their time course.

The role of target–distractor relationships in guiding attention and the eyes in visual search.

Current models of visual search assume that visual attention can be guided by tuning attention toward specific feature values (e.g., particular size, color) or by inhibiting the features of the irrelevant nontargets. The present study demonstrates that attention and eye movements can also be guided by a relational specification of how the target differs from the irrelevant distractors (e.g., larger, redder, darker). Guidance by the relational properties of the target governed intertrial priming effects and capture by irrelevant distractors. First, intertrial switch costs occurred only upon reversals of the coarse relationship between target and nontargets, but they did not occur when the target and nontarget features changed such that the relation remained the same. Second, irrelevant distractors captured most strongly when they differed in the correct direction from all other items--despite the fact that they were less similar to the target. This suggests that priming and contingent capture, which have previously been regarded as prime evidence for feature-based selection, are really due to a relational selection mechanism. Here I propose a new relational vector account of guidance, which holds promise to synthesize a wide range of different findings that have previously been attributed to different mechanisms of visual search.

Can intertrial priming account for the similarity effect in visual search?

In a visual search task, a salient distractor often elongates response times (RTs) even when it is task-irrelevant. These distraction costs are larger when the irrelevant distractor is similar than when dissimilar to the target. In the present study, we tested whether this similarity effect is mostly due to more frequent oculomotor capture by target-similar versus target-dissimilar distractors ( contingent capture hypothesis), or to elongated dwell times on target-similar versus dissimilar distractors ( attentional disengagement hypothesis), by measuring the eye movements of the observers during visual search. The results showed that similar distractors were both selected more frequently, and produced longer dwell times than dissimilar distractors. However, attentional capture contributed more to the similarity effect than disengagement. The results of a second experiment showed that stronger capture by similar than dissimilar distractors in part reflected intertrial priming effects: distractors which had the same colour as the target on the previous trial were selected more frequently than distractors with a different colour. These priming effects were however too small to account fully for the similarity effect. More importantly, the results indicated that allegedly stimulus-driven intertrial priming effects and allegedly top-down controlled similarity effects may be mediated by the same underlying mechanism.

Top-down influences on attentional capture by color changes

Previous studies have shown that a change in an existing object is not as effective in capturing attention as the appearance of a new object. This view was recently challenged by Lu and Zhou (Psychonomic Bulletin and Review 12:567-572, 2005), who found strong capture effects for an object changing its color. We suspected that this finding critically depends on a procedural particularity in Lu and Zhou's study, namely that the color of the unique item and the color of the no-unique items randomly switched between trials. In the current study we replicate Lu and Zhou's capture effect (Experiment 1) and show that no capture occurs when the color-to-stimuli assignment is fixed (Experiment 2). Two further experiments suggest that the capture effect in Experiment 1 is not because the unique item switched color (Experiment 3), but because all the no-unique items switched color (Experiment 4). The results are discussed considering top-down modulation and inter-trial priming effects.

Intertrial target-feature changes do not lead to more distraction by singletons: Target uncertainty does

The presence of an irrelevant singleton disrupts search for a singleton target substantially more when the target feature varies unpredictably (mixed-singleton search) than when it is known in advance (fixed-singleton search). This finding suggests that advance knowledge of the target feature guides singleton search. Pinto et al. [Pinto, Y., Olivers, C. N. L., & Theeuwes, J. (2005). Target uncertainty does not lead to more distraction by singletons: Intertrial priming does. Perception & Psychophysics, 67, 1354–1361] proposed an alternative account, according to which this difference results from inter-trial priming effects. They based their argument on the finding that distractor interference is reduced when the singleton target feature repeats vs. switches from one trial to the next. However, Lamy et al. [Lamy, D., Carmel, T., Egeth, H., & Leber, A. (2006). Effects of search mode and inter-trial priming on singleton search. Perception & Psychophysics, 68, 919–932] reported no such modulation of distractor interference by target-feature repetition. Here, we show that differences in design (blocking conditions of distractor presence in the former study vs. randomly mixing them in the latter) account for this discrepancy. We conclude that the different task demands induced by the blocked distractor-present and distractor-absent conditions rather than distractor presence per se interact with intertrial priming effects. These findings argue against the claim that singleton search relies exclusively on stimulus-driven factors and suggest that preknowledge of the target feature, when available, can guide attention. In addition, the present results challenge the ambiguity hypothesis of intertrial priming, according to which increased competition for attentional selection boosts inter-trial priming effects.

ポップアウトの試行間促進効果に対する注意の構えとプライミングの影響

In visual search situations, it is known that not only bottom-up factors relative to the presented stimulus display but also top-down factors, which include foreknowledge about the target or observers' strategies for the task, have an influence on search performance. The present study examines how top-down attentional control settings affect the visual search process by using the within-dimension facilitation (WDF) and the inter-trial facilitation (ITF) effects. In Experiment 1 we showed the WDF effect using foreknowledge about the target-defining dimension within one block. In Experiment 2 we found the ITF effect using foreknowledge about the target-defining dimension in every trial. These results suggest that search performance is improved both top-down attentional setting using foreknowledge and inter-trial priming by repetition of target-defining dimensions, and they are interactive. Furthermore, the influence of the priming effect strongly appeared when observers had an attentional setting every trial. These results show that the magnitude of bottom-up inter-trial priming effects depends on the top-down attentional setting.