Processes involved in the computation of a shape description.

The encoding of shape information from spatially separate items was investigated in 3 experiments. In Experiment 1a, participants had to search for an inward-pointing arc among a set of outward-pointing arcs; participants in Experiment 1b were given the opposite task. Search was efficient if distractor arcs pointed away from fixation and there was curvilinearity between neighboring end-terminators (Experiment 1a) but relatively inefficient if distractor arcs pointed toward fixation (Experiment 1b). In Experiments 2 and 3, connecting end terminators did not change performance. Results reflect the involvement of mechanisms of shape encoding. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Roles of salience and strategy in conjunction search.

In some cases, the search for a conjunction target proceeds through the smaller group of elements in a display, whereas in others, search is limited to those elements that share a particular feature with the target. In 6 experiments, participants searched for a conjunction target among displays consisting of various proportions of 2 distractor types. Smaller-group search was more prevalent than target-feature search with denser displays and with features that were highly discriminable. Explicit instructions to limit search to a specific feature affected performance only when the discriminability of the guiding feature was much greater than the other target feature. Together, these experiments show that bottom-up factors have more influence in guiding conjunction searches than previously thought. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A role for Cdc42 in macrophage chemotaxis

Grammatical morphemes, such as articles and auxiliary verbs, provide potentially useful information to language learners. However, children with specific language impairment (SLI) frequently fail to produce grammatical morphemes, raising questions about their sensitivity to them. To address this issue, two experiments were conducted in which 3- to 5-year-old children with SLI and with normally developing language (NL) heard sentences asking them to identify a picture corresponding to a named target word. The target occurred in either a grammatical sentence or one with an incorrectly used grammatical morpheme. In Experiment 1, the picture representing the target occurred with three unrelated distractor pictures. In Experiment 2, distractor sets included pictures that were semantically related to the target. In both studies, the SLI group chose fewer correct pictures when the target followed an incorrectly used morpheme. In Experiment 2, the SLI group chose more semantically related than unrelated distractors. These results suggest that children with SLI are sensitive to grammatical morphemes and that their incorrect picture choices may reflect a failure to maintain the target in memory.     

When danger lurks in the background: Attentional capture by animal fear-relevant distractors is specific and selectively enhanced by animal fear.

Across 2 experiments, a new experimental procedure was used to investigate attentional capture by animal fear-relevant stimuli. In Experiment 1 (N = 34), unselected participants were slower to detect a neutral target animal in the presence of a spider than a cockroach distractor and in the presence of a snake than a large lizard distractor. This result confirms that phylogenetically fear-relevant animals capture attention specifically and to a larger extent than do non-fear-relevant animals. In Experiment 2 (N = 86), detection of a neutral target animal was slowed more in the presence of a feared fear-relevant distractor (e.g., a snake for snake-fearful participants) than in presence of a not-feared fear-relevant distractor (e.g., a spider for snake-fearful participants). These results indicate preferential attentional capture that is specific to phylogenetically fear-relevant stimuli and is selectively enhanced in individuals who fear these animals. (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)     

Personal names and the attentional blink: a visual "cocktail party" effect

Four experiments were carried out to investigate an early- versus late-selection explanation for the attentional blink (AB). In both Experiments 1 and 2, 3 groups of participants were required to identify a noun (Experiment 1) or a name (Experiment 2) target (experimental conditions) and then to identify the presence or absence of a 2nd target (probe), which was their own name, another name, or a specified noun from among a noun distractor stream (Experiment 1) or a name distractor stream (Experiment 2). The conclusions drawn are that individuals do not experience an AB for their own names but do for either other names or nouns. In Experiments 3 and 4, either the participant's own name or another name was presented, as the target and as the item that immediately followed the target, respectively. An AB effect was revealed in both experimental conditions. The results of these experiments are interpreted as support for a late-selection interference account of the AB.     

Detection of Kanji words in a rapid serial visual presentation task.

In 3 experiments, lists of 12 Kanji words were rapidly presented in the same position, and participants reported a red target word embedded in green distractor words. Two lists were used: same and different category. A tendency toward category priming was found at longer durations. Frequency of target localization indicated that participants familiar with Kanji had a greater tendency to report the word immediately preceding the target. These pretarget intrusion errors dominated the posttarget intrusion errors, when the luminance of red and green stimuli were equated (Experiment 2), and when the response was recall (Experiments 1 and 2) or recognition (Experiment 3). In contrast, participants unfamiliar with Kanji made posttarget intrusion errors as frequently as pretarget intrusion errors (Experiment 3), suggesting that knowledge of Kanji influences the integration of color and form codes in visual information processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatiotemporal Segregation in Visual Search: Evidence From Parietal Lesions.

The mechanisms underlying segmentation and selection of visual stimuli over time were investigated in patients with posterior parietal damage. In a modified visual search task, a preview of old objects preceded search of a new set for a target while the old items remained. In Experiment 1, control participants ignored old and prioritized new items, but patients had severe difficulties finding the target (especially on the contralesional side). In Experiment 2, simplified displays yielded analogous results, ruling out search ease as a crucial factor in poor preview search. In Experiment 3, outlines around distractor groups (to aid segmentation) improved conjunction but not preview search, suggesting a specific deficit in spatiotemporal segmentation. Experiment 4 ruled out spatial disengagement problems as a factor. The data emphasize the role of spatiotemporal segmentation cues in preview search and the parietal lobe in the role of these cues to prioritize search of new stimuli. (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)     

Identity negative priming in older adults and individuals with dementia of the Alzheimer type.

This study addressed the question of whether dementia of the Alzheimer type (DAT) produces a breakdown in aspects of the inhibitory component underlying selective attention. Two measures of identity negative priming and 2 measures of distractor interference were obtained. In Experiment 1, participants were presented with overlapping picture stimuli, and in Experiment 2, participants were presented with overlapping written word stimuli. The results of both experiments produced reliable and similar size negative priming in young and old adults, but there was no evidence of negative priming in the individuals with DAT. In contrast, the naming latencies of all 3 groups showed a reliable and similar size distractor interference effect. These results suggest that although the inhibitory component underlying selective attention is impaired in individuals with DAT, the ability to differentiate a target from a distractor may be preserved under certain task conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gaze perception requires focused attention: Evidence from an interference task.

The direction of another person's gaze is difficult to ignore when presented at the center of attention. In 6 experiments, perception of unattended gaze was investigated. Participants made directional (left-right) judgments to gazing-face or pointing-hand targets, which were accompanied by a distractor face or hand. Processing of the distractor was assessed via congruency effects on target response times. Congruency effects were found from the direction of distractor hands but not from the direction of distractor gazes (Experiment 1). This pattern persisted even when distractor sizes were increased to compensate for their peripheral presentation (Experiments 2 and 5). In contrast, congruency effects were exerted by profile heads (Experiments 3 and 4). In Experiment 6, isolated eye region distractors produced no congruency effects, even when they were presented near the target. These results suggest that, unlike other facial information, gaze direction cannot be perceived outside the focus of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-trial priming of element positions in visual pop-out search is dependent on stimulus arrangement.

Two experiments examined cross-trial positional priming (V. Maljkovic & K. Nakayama, 1994, 1996, 2000) in visual pop-out search. Experiment 1 used regularly arranged target and distractor displays, as in previous studies. Reaction times were expedited when the target appeared at a previous target location (facilitation relative to neutral baseline) and slowed when the target appeared at a previous distractor location (inhibition). In contrast to facilitation, inhibition emerged only after extended practice. Experiment 2 revealed reduced facilitatory and no inhibitory priming when the elements' spatial arrangement was made irregular, indicating that positional--in particular, inhibitory--priming critically depends on the configuration of the display elements across sequences of trials. These results are discussed with respect to the role of the context for cross-trial priming in visual pop-out search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Capacity demands of phoneme selection in word production: New evidence from dual-task experiments.

Three dual-task experiments investigated the capacity demands of phoneme selection in picture naming. On each trial, participants named a target picture (Task 1) and carried out a tone discrimination task (Task 2). To vary the time required for phoneme selection, the authors combined the targets with phonologically related or unrelated distractor pictures (Experiment 1) or words, which were clearly visible (Experiment 2) or masked (Experiment 3). When pictures or masked words were presented, the tone discrimination and picture naming latencies were shorter in the related condition than in the unrelated condition, which indicates that phoneme selection requires central processing capacity. However, when the distractor words were clearly visible, the facilitatory effect was confined to the picture naming latencies. This pattern arose because the visible related distractor words facilitated phoneme selection but slowed down speech monitoring processes that had to be completed before the response to the tone could be selected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interhemispheric stroop-like interference in number comparison: Evidence for strong interhemispheric integration of semantic number information.

Three experiments investigated interhemispheric interactions in number comparison using the interhemispheric Stroop-like paradigm (E. Ratinckx, M. Brysbaert, & B. Reynvoet, 2001). In all experiments, a target was presented in 1 visual field simultaneously with a distractor in the other visual field. In Experiment 1, both target and distractor were of the same modality (Arabic digits), whereas in Experiment 2, target and distractor were of different modalities (Arabic digits and word numerals). In Experiment 3, the interhemispheric Stroop-like task of Experiment 1 was combined with intrahemispheric conditions to evaluate the strength of the interhemispheric interactions. Overall, the results point to strong interhemispheric integration during semantic access and response preparation with very weak lateralization of the semantic number system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of a moving distractor object on time-to-contact judgments.

The effects of moving task-irrelevant objects on time-to-contact (TTC) judgments were examined in 5 experiments. Observers viewed a directly approaching target in the presence of a distractor object moving in parallel with the target. In Experiments 1 to 4, observers decided whether the target would have collided with them earlier or later than a standard (absolute identification task). A contrast effect was observed: If the distractor arrived later than the target, it caused a bias toward early responses, relative to the condition without a distractor. The early-arriving distractor had no significant effect. The pattern of results was unaltered when potentially confounding information from individual visual cues was removed. The availability of stereoscopic information reduced the effect. The contrast effect was also observed if target and distractor were abstract geometric objects rather than simulations of real-world vehicles, rendering less likely a simple safety strategy activated by a potentially threatening distractor. Experiment 5 showed that the effect of the late-arriving distractor generalized to a prediction-motion task. The results indicate that task-irrelevant information in the background has to be considered in revision of time-to-contact theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in working memory capacity and episodic retrieval: Examining the dynamics of delayed and continuous distractor free recall.

Two experiments explored the possibility that individual differences in working memory capacity (WMC) partially reflect differences in the size of the search set from which items are retrieved. High- and low-WMC individuals were tested in delayed (Experiment 1) and continuous distractor (Experiment 2) free recall with varying list lengths. Across both experiments low-WMC individuals recalled fewer items than high-WMC individuals, recalled more previous list intrusions than high-WMC individuals, and recalled at a slower rate than high-WMC individuals. It is argued that low-WMC individuals' episodic retrieval deficits are partially due to the fact that these individuals search through a larger set of items than high-WMC individuals. Simulations based on a random search model were consistent with these general conclusions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for episodic retrieval of inadequate prime responses in auditory negative priming.

Four experiments are reported in which the mechanisms underlying auditory negative priming were investigated. In Experiments 1A and 1B, preprime-prime intervals and prime-probe intervals were manipulated. The ratio between the 2 intervals determined the size of the negative priming effect. Results are compatible with the episodic retrieval account, according to which the retrieval of inappropriate response information associated with the previous distractor slows down responding when that stimulus becomes the target. Experiment 2 tested a variant of this account, according to which the retrieval of the prime response rather than the retrieval of nonresponse information interferes with responding. Consistent with this variant, participants erroneously responded with the prime response more frequently in the ignored repetition condition than in the control condition. Experiment 3 replicated this finding and generalized it to the visual modality. The authors conclude that the retrieval of the inappropriate prime response is a determinant of the negative priming phenomenon. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Response Selection in Visual Search: The Influence of Response Compatibility of Nontargets.

The authors used visual search tasks in which components of the classic flanker task (B. A. Eriksen & C. W. Eriksen, 1974) were introduced. In several experiments the authors obtained evidence of parallel search for a target among distractor elements. Therefore, 2-stage models of visual search predict no effect of the identity of those distractors. However, clear compatibility effects of the distractors were obtained: Responses were faster when the distractors were compatible with the response than when they were incompatible. These results show that even in parallel search tasks identity information is extracted from the distractors. In addition, alternative interpretations of the results in terms of the occasional identification of a distractor before or after the target was identified could be ruled out. The results showed that flat search slopes obtained in visual search experiments provide no benchmark for preattentive processing. (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)