"Transient structures": the effects of practice and distractor grouping on within-dimension conjunction searches

It has been stated that whereas between-dimension (color x orientation) conjunctions can be searched in a "parallel" fashion, within-dimension (color x color) conjunctions are necessarily searched in a "serial self-terminating" fashion (Wolfe et al., 1990). We explored the effects of practice (within 1-h experimental session) and distractor grouping on within-dimension conjunction search tasks. In Experiments 1 and 3, the stimuli were rectangles formed by two adjacent squares; in Experiment 2, the stimuli were plus signs formed by two segments and an intersection. In Experiments 1 and 2, observers were assigned to one of two experimental conditions: In one, all the distractors shared a simple feature (the color blue); in the other, distractors did not share that simple feature. In the first condition, search became more efficient with practice and observers' performance was characterized by a shallow reaction time (RT) x set size slope; in the second condition, observers' performance did not improve as much with practice. We propose that the differential effects of practice between these two experimental conditions can be explained in terms of distractor grouping induced by the shared color of the distractors. Experiment 3 showed that, with practice, a shallow RT x set size slope characterized observers' search for a color x color target among four different distractors that shared a common color. The present results contradict a main tenet of some current visual search models--namely, that within-dimension conjunctions cannot be searched in parallel, and question the validity of using RT x set size slope functions to distinguish between preattentive versus attentive search.     

Look Here but Ignore What You See: Effects of Distractors at Fixation.

Distractor interference effects were compared between distractors in the periphery and those placed at fixation. In 6 experiments, the authors show that fixation distractors produce larger interference effects than peripheral distractors. However, the fixation distractor effects are modulated by perceptual load to the same extent as are peripheral distractor effects (Experiments 1 and 2). Experiment 3 showed that fixation distractors are harder to filter out than peripheral distractors. The larger distractor effects at fixation are not due to the cortical magnification of foveal stimuli (Experiments 4 and 5), nor can they be attributed to cuing by the fixation point (Experiment 2), the lower predictability or greater location certainty of fixation distractors (Experiment 5), or their being in a central position (Experiment 6). The authors suggest that preferential access to attention renders fixation distractors harder to ignore than peripheral distractors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional control during visual search: the effect of irrelevant singletons

Four experiments investigated whether a highly salient color singleton can be ignored during serial search. Observers searched for a target letter among nontarget letters and were instructed to ignore an irrelevant, highly salient color singleton that was either compatible or incompatible with the response to the target letter. The results indicate that it was possible to prevent attentional capture by the irrelevant singleton only when both the target and the distractor color were known. When either the color of the target or the color of the to-be-ignored singleton were varied over trials, the irrelevant singleton captured attention. The ability to selectively filter singleton distractors during serial search depends on the presence of an attentional set for a specific feature value of both target and distractor. In the absence of a consistently predictable feature value of both target and distractor, top-down control is not possible.     

Habituation to auditory distractors in a cross-modal, color–word interference task.

The speed of naming the color of a colored square was examined with acoustic distraction to study the effects of the formation of a mental representation (neural model) of distractors. In Experiment 1, practice with the distractors (color words, noncolor words, and tones) was examined, and in Experiments 2 and 3 each color-naming trial was preceded by preexposures to sounds that could be dissimilar, similar, or identical to the upcoming auditory distractor. Consistency in the identity of ignored sounds, whether during color-naming practice or between preexposures and test, reduced interference with color naming. Consistency in voice played no role, and attended preexposures were ineffective in reducing interference. Given these results, the authors propose that mental representations of distractors include information about their task relevance, which modulates disruption of the primary task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Precuing target location in a variable set size "nonsearch" task: Dissociating search-based and interference-based explanations for set size effects.

If a target's location is validly cued before a variable set size display, then an effect of set size on detection would indicate distractor interference rather than search. Observers performed a 1-, 3-, or 5-item detection task (indicate the presence or absence of a realistic target in the context of conceptually consistent distractors) under conditions of valid or neutral spatial precuing. Results from Experiment 1, and a replication blocking cue condition (Experiment 2), indicated set size effects in the cued target-present, but not target-absent, data. Experiment 3 determined that this interference was not due to a semantic relationship between target and distractors, and Experiment 4 used a preview paradigm to argue against distractor onsets as a source of interference. Experiment 5 eliminated this interference-based set size effect by having observers preposition their eyes over the cued location in the detection scene. Findings provide evidence for a set size effect in the absence of search and suggest that distractors may systematically diminish a visual preparatory priming advantage normally benefiting target-present detection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How attentional systems process conflicting cues. The superiority of social over symbolic orienting revisited.

We investigated orienting of attention by social and symbolic cues presented inside/outside the locus of attention. Participants responded to laterally presented targets preceded by simultaneously presented gaze and arrow cues. Participants’ attention was allocated to either of the cues and the other cue served as a distractor. In Experiments 1–4 nonpredictive cues were employed. The validity of the attended cue and distractor were varied orthogonally. Valid cues and distractors produced additive facilitation to reaction times when compared to invalid cues and distractors. The effects of gaze and arrow distractors were similar. When the cue was 100% valid and the distractor 50% valid (Experiment 5), distractor validity had no effect on reaction times. When realistic gaze and arrow cues were employed (Experiment 6), arrow but not gaze distractors influenced the reaction times. The results suggest that social and symbolic directional information can be integrated for attention orienting. The processing of social and symbolic directional information can be modulated by top-down control, but the efficiency of the control depends on the visual saliency of the cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search for singleton feature targets across dimensions: Stimulus- and expectancy-driven effects in dimensional weighting.

Four pop-out search experiments investigated whether dimension-based visual attention is top-down modulable. Observers searched for singleton feature targets defined, variably across trials, by a color or an orientation difference to nontargets. Observers were precued to the most probable target-defining dimension (e.g., by the word color) or feature (red) on a given trial. Results revealed expedited reaction times (RTs) for valid-dimension targets relative to neutral-cue conditions, and slowed RTs for invalid-dimension targets. Cue information as to precise target feature yielded some extra effect only for color targets. The dimensional cuing significantly reduced, but did not abolish, the dimension-specific influence of the previous target on detection of the current target (same-dimension RT     

Adult Age Differences in the Implicit and Explicit Components of Top-Down Attentional Guidance During Visual Search.

Two experiments investigated adult age differences in the explicit (knowledge-based) and implicit (repetition priming) components of top-down attentional guidance during discrimination of a target singleton. Experiment 1 demonstrated an additional contribution of explicit top-down attention, relative to the implicit effect of repetition priming, which was similar in magnitude for younger and older adults. Experiment 2 examined repetition priming of target activation and distractor inhibition independently. The additional contribution of explicit top-down attention, relative to the repetition priming of distractor inhibition, was greater for older adults than for younger adults. The results suggest that some forms of top-down attentional control are preserved as a function of adult age and may operate in a compensatory manner. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing segmental and prosodic information in Cantonese word production.

Five experiments were conducted to investigate how subsyllabic, syllabic, and prosodic information is processed in Cantonese monosyllabic word production. A picture-word interference task was used in which a target picture and a distractor word were presented simultaneously or sequentially. In the first 3 experiments with visually presented distractors, null effects on naming latencies were found when the distractor and the picture name shared the onset, the rhyme, the tone, or both the onset and tone. However, significant facilitation effects were obtained when the target and the distractor shared the rhyme + tone (Experiment 2), the segmental syllable (Experiment 3), or the syllable + tone (Experiment 3). Similar results were found in Experiments 4 and 5 with spoken rather than visual distractors. Moreover, a significant facilitation effect was observed in the rhyme-related condition in Experiment 5, and this effect was not affected by the degree of phonological overlap between the target and the distractor. These results are interpreted in an interactive model, which allows feedback sending from the subsyllabic to the lexical level during the phonological encoding stage in Cantonese word production. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Irrelevant singletons in pop-out search: Attentional capture or filtering costs?

The aim of the present study was to investigate whether costs invoked by the presence of an irrelevant singleton distractor in a visual search task are due to attentional capture by the irrelevant singleton or spatially unrelated filtering costs. Measures of spatial effects were based on distance effects, compatibility effects, and differences between singleton and nonsingleton target trials. The results show that the distractor only regularly captures attention when it is nonpredictive of the target position and unpredictably changes its features. When the distractor is antipredictive of the target position and the irrelevant features of target and distractor remain constant throughout the experiment, spatially unrelated filtering costs prevail. Further experiments showed that filtering costs accrue from distractor inhibition or target activation processes, which in turn can be modeled as instances of priming of pop-out. The present study thus clarifies the notion of filtering costs and modifies present accounts of the distraction effect. Moreover, the results also relate to research of intertrial priming by showing that priming affects the stage of attentional selection and depends on top-down attentional control settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grasping a fruit: Selection for action.

This study used a natural task, with no emphasis placed on speeded responses, to investigate unconscious information processing. Using the ELITE system, a kinematic analysis was performed of the upper limb reach-to-grasp movement. Nine experiments explored how the presence of distractors affects the transport and grasp component of this movement. Experiment 1showed that the kinematics for grasping apples, mandarins, cherries, and bananas were measurably different. Experiments 2A–D, 3, and 4 showed that these kinematics were not affected by the presence of nearby distractor fruits of either the same or a different kind. In Experiment 5, interference effects became evident when participants were required to perform a subsidiary task involving the distractor (counting the number of times a laterally placed fruit was illuminated). Experiment 6, requiring both grasping a target fruit and counting the number of times that this fruit was illuminated, revealed no interference effects. Taken together, these results suggest that selection for action does not involve substantial passive processing of distractors. However, dual-action processing of simultaneously presented objects does appear to involve automatic processing of even the task-irrelevant properties of the distractor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual grouping and visual selective attention

The present study demonstrates that incongruent distractor letters at a constant distance from a target letter produce more response competition and negative priming when they share a target's color than when they have a different color. Moreover, perceptual grouping by means of color, attenuated the effects of spatial proximity. For example, when all items were presented in the same color, near distractors produced more response competition and negative priming than far distractors (Experiment 3A). However, when near distractors were presented in a different color and far distractors were presented in the same color as the target, the response competition x distractor proximity interaction was eliminated and the proximity x negative priming interaction was reversed (Experiment 3B). A final experiment demonstrated that distractors appearing on the same object as a selected target produced comparable amounts of response competition and negative priming whether they were near or far from the target. This suggests that the inhibitory mechanisms of visual attention can be directed to perceptual groups/objects in the environment and not only to unsegmented regions of visual space.     

The Gender Congruency Effect and the Selection of Freestanding and Bound Morphemes: Evidence From Croatian.

The authors report 3 picture-word interference experiments in which they explore some properties of the agreement process in speech production. In Experiment 1, Croatian speakers were asked to produce utterances in which the noun's gender value had an impact on the selection of gender-marked freestanding morphemes (pronouns) while ignoring the presentation of same- or different-gender distractor words. In Experiments 2 and 3, Croatian speakers were asked to name the same pictures using noun phrases in which the noun's gender value surfaced as an inflectional suffix. Different-gender distractors interfered more than same-gender distractors (the gender congruency effect) in Experiment 1, but not in Experiments 2 and 3. These contrasting results show that the cause of the gender congruency effect is not at the level where lexical-grammatical information is selected but at the level of selection of freestanding morphemes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Top-down control over biased competition during covert spatial orienting.

Larger benefits of spatial attention are observed when distractor interference is prevalent, supporting the view that spatial selection facilitates visual processing by suppressing distractor interference. The present work shows that cuing effects with identical visual displays can grow substantially as the probability of distractor interference increases. The probability of interference had no impact on spatial cuing effects in the absence of distractors, suggesting that the enlarged cuing effects were not caused by changes in signal enhancement or in the spatial distribution of attention. These findings suggest that attentional control settings determine more than where spatial attention is directed; top-down settings also influence how attention affects visual processing, with increased levels of distractor exclusion when distractor interference is likely. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distractor devaluation effect in the attentional blink: Direct evidence for distractor inhibition.

When two targets (T1 and T2) are embedded in rapid serial visual presentation (RSVP), T2 is often missed (attentional blink, AB) if T2 follows T1 by less than 500 ms. Some have proposed that inhibition of a distractor following T1 contributes to the AB, but no direct evidence supports this proposal. This study examined distractor inhibition by assessing a distractor devaluation effect where inhibited items were evaluated less positively than controls. Experiments 1 and 2 showed that a distractor presented just after T1 was evaluated less favorably when T2 was misidentified, independently of stimulus characteristics. Experiment 3 produced distractor devaluation in T2 incorrect trials when the evaluated distractor was the second item after T1. In contrast, a distractor presented before T1 was not devaluated (Experiment 4). Experiment 5 demonstrated that participants could not recognize presented distractors after an RSVP task, rejecting the possibility that memorized distractors were devalued. Results show a relationship between the devaluation of distractors following T1 and the AB, providing the first direct evidence of the distractor inhibition during the AB. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus repetition effects on texture-based visual search by pigeons.

Four experiments investigated the effects of within-session stimulus repetition on texture discrimination. Six pigeons (Columba livia) searched for a contrasting target region (color or shape) randomly embedded within a larger distractor region for food reinforcement. Experiment 1 found that repeating features of the distractors, but not those of the target, across trials increased the accuracy of target localization relative to baseline. Experiment 2 found that subsequently switching the identity of a repeated distractor feature to the target decreased accuracy. Experiment 3 found that the effects of repeating a distractor feature influenced search performance for at least 60 trials after this learning. Experiment 4 found that differential stimulus-outcome relations can produce control by repeated target features. The results are discussed in terms of the factors and strategies involved in the control of avian visual search behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A two-stage model for multiple target detection in rapid serial visual presentation.

When 2 targets are presented among distractors in rapid serial visual presentation, correct identification of the 1st target results in a deficit for a 2nd target appearing within 200–500 ms. This attentional blink (AB; J. E. Raymond, K. L. Shapiro, & K. M. Arnell, 1992) was examined for categorically defined targets (letters among nonletters) in 7 experiments. AB was obtained for the 2nd letter target among digit distractors (Experiment 1) and also for a 3rd target (Experiment 2). Results of Experiments 3–5 confirmed that AB is triggered by local interference from immediate posttarget stimulation (Raymond et al., 1992) and showed that AB is modulated by the discriminability between the 1st target and the immediately following distractor. Experiments 5–7 further examined the effects of both local interference and global discriminability. A 2-stage model is proposed to account for the AB results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Active inhibition of a distractor word: The distractor precue benefit in the Stroop color-naming task.

The current study investigated attentional control through active inhibition of the identity of the distractor. Adapting a Stroop paradigm, the distractor word was presented in advance and made to disappear, followed by the presentation of a Stroop stimulus. Participants were instructed to inhibit the distractor in order to reduce its interference. Experiments 1 and 2 demonstrated that the distractor precue facilitated Stroop color naming by reducing Stroop interference. Experiment 3 demonstrated beneficial effects of the distractor precue when congruent trials were introduced. Experiment 4 showed that the distractor precue benefit was observed when the cue and target were in different forms. Experiment 5 indicated that if the item used as the cue became the target, naming it took longer in order to overcome the inhibitory effect. Experiment 6 demonstrated that the benefit of the distractor precue was not observed when the cue was uninformative. Finally, Experiment 7 demonstrated that active inhibition required working-memory resources to operate. This study suggests that the best explanation for the distractor precue benefit is the active inhibition account. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Distractor modality can turn semantic interference into semantic facilitation in the picture–word interference task: Implications for theories of lexical access in speech production.

A number of recent studies have questioned the idea that lexical selection during speech production is a competitive process. One type of evidence against selection by competition is the observation that in the picture–word interference task semantically related distractors may facilitate the naming of a picture, whereas the selection by competition account predicts them to interfere. In the experiments reported in this article, the authors systematically varied, for a given type of semantic relation—that is, basic-level distractors (e.g., fish) during subordinate-level naming (e.g., carp)—the modality in which distractor words were presented (auditory vs. visual) and the proportion of response-congruent trials (i.e., trials allowing for the correct naming response to be derived from both the distractor and the target). With auditory distractors, semantic interference was obtained irrespective of the proportion of response-congruent trials (low in Experiment 1, high in Experiment 2). With visual distractors, no semantic effect was obtained with a low proportion of response-congruent trials (Experiment 3), whereas a semantic facilitation effect was obtained with a high proportion of response-congruent trials (Experiment 4). The authors propose that two processes contribute to semantic effects observed in the picture–word interference paradigm, namely selection by competition (leading to interference) and response congruency (leading to facilitation). Whether facilitation due to response congruency overrules the interference effect because of competition depends on the relative strength of these two processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)