The remains of the trial: goal-determined inter-trial suppression of selective attention

Association between cue lead time and template-for-rejection effect

The human visual system can actively prioritize task-relevant features to search for a target. Recent studies have reported cases in which the system may suppress irrelevant features by using a template for rejection. However, in those studies, the templates used for rejection were limited to the color domain, and they have yielded mixed results. Our literature review identified three differences among studies that may be responsible for such mixed results: differences in the spatial segmentation of items (i.e., segregated or intermixed across the display), differences in how features are defined and reported (i.e., combined or separate), and differences in cue lead times (short or long). Participants searched for a target-line segment in a shape and identified its orientation from among non-target line-shaped compound shapes that were preceded by one of three cue displays. Positive cues indicated that the target segment would appear in a shape, and negative cues that it would not appear in a shape. Neutral cues indicated that a particular shape would not appear in the current search display. The results demonstrated that reaction times were faster under the negative-cue condition than the neutral-cue condition, reflecting the effect of a shape-based template for rejection (Experiment 1). Experiment 2 replicated the absence of the effect in the shape domain. Experiment 3 indicated that the template-for-rejection effect occurred only when the cue lead time was relatively long, suggesting that time is required (approximately 2,400 ms or longer) for the visual system to form rejection templates. Experiment 4 excluded the possibility that a confound in the target-defining/reporting feature was involved. These results indicated that apparent inconsistencies in research on the template-for-rejection effect can be explained in terms of the time required for templates to be configured.

Electrophysiological revelations of trial history effects in a color oddball search task

In visual oddball search tasks, viewing a no-target scene (i.e., no-target selection trial) leads to the facilitation or delay of the search time for a target in a subsequent trial. Presumably, this selection failure leads to biasing attentional set and prioritizing stimulus features unseen in the no-target scene. We observed attention-related ERP components and tracked the course of attentional biasing as a function of trial history. Participants were instructed to identify color oddballs (i.e., targets) shown in varied trial sequences. The number of no-target scenes preceding a target scene was increased from zero to two to reinforce attentional biasing, and colors presented in two successive no-target scenes were repeated or changed to systematically bias attention to specific colors. For the no-target scenes, the presentation of a second no-target scene resulted in an early selection of, and sustained attention to, the changed colors (mirrored in the frontal selection positivity, the anterior N2, and the P3b). For the target scenes, the N2pc indicated an earlier allocation of attention to the targets with unseen or remotely seen colors. Inhibitory control of attention, shown in the anterior N2, was greatest when the target scene was followed by repeated no-target scenes with repeated colors. Finally, search times and the P3b were influenced by both color previewing and its history. The current results demonstrate that attentional biasing can occur on a trial-by-trial basis and be influenced by both feature previewing and its history.

Not all "distractor" tags are created equal: using a search asymmetry to dissociate the inter-trial effects caused by different forms of distractors

In a typical pop-out task, there is one target and a varying number of distractor stimuli. Now imagine a target-absent display in the context of a pop-out task: all items are identical, and it is decidedly easy to conclude that all items in the display are distractors, precisely because there is no target to select on that display. One may be tempted to say that, as far as the attention system is concerned, these two types of distractors are the same: target-present distractors and target-absent distractors. The present study proposes that this is actually not the case. Target-absent distractors can sometimes produce inter-trial effects that their close-cousins, the target-present distractors, cannot. We used a letters/numbers categorical oddball task to demonstrate this difference. The results are interpreted in the context of recent findings in cognitive neuroscience as well as cognitive modeling.

Modeling the effect of selection history on pop-out visual search

While attentional effects in visual selection tasks have traditionally been assigned “top-down” or “bottom-up” origins, more recently it has been proposed that there are three major factors affecting visual selection: (1) physical salience, (2) current goals and (3) selection history. Here, we look further into selection history by investigating Priming of Pop-out (POP) and the Distractor Preview Effect (DPE), two inter-trial effects that demonstrate the influence of recent history on visual search performance. Using the Ratcliff diffusion model, we model observed saccadic selections from an oddball search experiment that included a mix of both POP and DPE conditions. We find that the Ratcliff diffusion model can effectively model the manner in which selection history affects current attentional control in visual inter-trial effects. The model evidence shows that bias regarding the current trial's most likely target color is the most critical parameter underlying the effect of selection history. Our results are consistent with the view that the 3-item color-oddball task used for POP and DPE experiments is best understood as an attentional decision making task.

Age-related differences in the distractor previewing effect with schematic faces of emotions

Young and older adults searched for a unique face in a set of three schematic faces and identified a secondary feature of the target. The faces could be negative, positive, or neutral. Young adults were slower and less accurate in searching for a negative face among neutral faces when they had previewed a display of negative faces than when they had previewed neutral faces, indicating an emotional distractor previewing effect (DPE), but this effect was eliminated with inverted faces. The DPE is an index of inter-trial inhibition to keep attention away from previewed, non-target information. Older adults also showed such an emotional DPE, but it was present with both upright and inverted faces. These results show that, in general, both young and old participants are sensitive to trial history, yet the different patterns of results suggest that these two groups remember and use different types of perceptual information when searching through emotional faces.

Category-based inhibition of focused attention across consecutive trials

The distractor previewing effect (DPE) refers to the behavioral phenomenon that search times increase for oddball targets containing features recently associated with the absence of a target. Previous work using a color-oddball search task showed that the DPE covaried with the N2pc component of the event-related potential (an index of attention allocation) but not with other components, suggesting that the DPE reflects shifts in attentional sets. We sought to determine whether the previous results could generalize to a category-oddball search task. Results showed that the DPE co-occurred with N2pc effects in about 60% of the participants, and the DPE occurred with no N2pc effects in the rest of the participants. These results support a domain-general, attention-based account of the DPE, but also suggest that the attention-based DPE account requires some modifications.