Does visual attention select objects or locations?

Much research supports location-based attentional selection, but J. Duncan (see record 1985-29839-001) presented data favoring object-based selection in a shape discrimination task. Does attention select objects or locations? The authors confirmed that Duncan's task elicits selection from spatially invariant object representations rather than from a grouped location-based representation. They next asked whether this finding was due to location-based filtering; the results again supported object-based selection. Finally, it was demonstrated that when Duncan's objects were used in a cued detection task, the results were consistent with location-based selection. These results suggest that there may be a single attention mechanism, consistent with Duncan's original claim that object-based and location-based attentional selection are not mutually exclusive. Rather, attentional limitations may depend on the type of stimulus representation used in performing a given task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Input control processes in rapid serial visual presentations: Target selection and distractor inhibition.

The attentional blink refers to the finding that the 2nd of 2 targets embedded in a stream of rapidly presented distractors is often missed. Whereas most theories of the attentional blink focus on limited-capacity processes that occur after target selection, the present work investigates the selection process itself. Identifying a target letter caused an attentional blink for the enumeration of subsequent dot patterns, but this blink was reduced when the dots shared their color with the target letter. In contrast, performance worsened when the color of the dots matched that of the remaining distractors in the stream. Similarity between the targets also affected competition between different sets of dots presented simultaneously within a single display. The authors conclude that the selection of targets from a rapid serial visual presentation stream is mediated by both excitatory and inhibitory attentional control mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional spreading in object-based attention.

The authors investigated 2 effects of object-based attention: the spread of attention within an attended object and the prioritization of search across possible target locations within an attended object. Participants performed a flanker task in which the location of the task-relevant target was fixed and known to participants. A spreading attention account predicts that object-based attention will arise from the spread of attention through an attended object. A prioritization account predicts that there will be a small, if any, object-based effect because the location of the target is known in advance and objects are not required to prioritize the deployment of attentional search. The results suggested that object-based attention operates via the spread of attention within an object. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grouped locations and object-based attention: Comment on Egly, Driver, and Rafal (1994).

Recently, R. Egly et al (see record 1994-34191-001) provided evidence for an object-based component of visual orienting in a simple cued reaction time task. However, the effects of objects on visual attention can be due to selection from either of 2 very different types of representations: (1) a truly object-based representation that codes for object structure or (2) a grouped array representation that codes for groups of spatial locations. Are Egly et al's results due to selection from an object-based representation or from a grouped array representation? This question was addressed by using a variant of Egly et al's task. The findings replicated those of Egly et al and demonstrated that the selection in this task is mediated through a grouped array representation. The implications of these results for studies of attentional selection are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrophysiological markers of visual dimension changes and response changes.

In cross-dimensional visual search tasks, target discrimination is faster when the previous trial contained a target defined in the same visual dimension as the current trial. The dimension-weighting account (DWA; A. Found & H. J. Müller, 1996) explains this intertrial facilitation by assuming that visual dimensions are weighted at an early perceptual stage of processing. Recently, this view has been challenged by models claiming that intertrial facilitation effects are generated at later stages that follow attentional target selection (K. Mortier, J. Theeuwes, & P. A. Starreveld, 2005). To determine whether intertrial facilitation is generated at a perceptual stage, at the response selection stage, or both, the authors focused on specific event-related brain potential components (directly linkable to perceptual and response-related processing) during a compound search task. Visual dimension repetitions were mirrored by shorter latencies and enhanced amplitudes of the N2-posterior- contralateral, suggesting a facilitated allocation of attentional resources to the target. Response repetitions and changes systematically modulated the lateralized readiness potential amplitude, suggesting a benefit from residual activations of the previous trial biasing the correct response. Overall, the present findings strengthen the DWA by indicating a perceptual origin of dimension change costs in visual search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The sparing is far from spurious: Reevaluating within-trial contingency effects in the attentional blink.

The attentional blink is the marked deficit in awareness of a 2nd target (T2) when it is presented shortly after the 1st target (T1) in a stream of distractors. When the distractors between T1 and T2 are replaced by even more targets, the attentional blink is reduced or absent, indicating that the attentional blink results from online selection mechanisms that act in response to distracting input rather than being the result of T1-induced cognitive resource depletion. However, Dell'Acqua, Jolicoeur, Luria, and Pluchino (2009) recently contended that an attentional blink is found in the multiple-target case as long as the appropriate trial context and analyses are used, thus reinstating resource-based explanations of the attentional blink and challenging the selection account. Specifically, an attentional blink reemerges when target performance is analyzed contingent on previous target accuracy. We argue on theoretical and empirical grounds that neither the trial context nor the type of analysis poses a serious problem for selection accounts. We show that the attentional blink and previous target contingency effects can be dissociated, with the latter depending more on low-level, short-range competition. We conclude that selection mechanisms involved in filtering for targets still provide a strong and coherent explanation of the attentional blink. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Attentional changes during implicit learning: Signal validity protects a target stimulus from the attentional blink.

Participants in 2 experiments performed 2 simultaneous tasks: one, a dual-target detection task within a rapid sequence of target and distractor letters; the other, a cued reaction time task requiring participants to make a cued left–right response immediately after each letter sequence. Under these rapid visual presentation conditions, it is usually difficult to identify the 2nd target when it is presented in temporal proximity of the 1st target—a phenomenon known as the attentional blink. However, here participants showed an advantage for detecting a target presented during the attentional blink if that target predicted which response cue would appear at the end of the trial. Participants also showed faster reaction times on trials with a predictive target. Both of these effects were independent of conscious knowledge of the target–response contingencies assessed by postexperiment questionnaires. The results suggest that implicit learning of the association between a predictive target and its outcome can automatically facilitate target recognition during the attentional blink and therefore shed new light on the relationship between associative learning and attentional mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object-based attentional selection—Grouped arrays or spatially invariant representations?: Comment on Vecera and Farah (1994).

S. P. Vecera and M. J. Farah (see record 1994-32352-001) have addressed the issue of whether visual attention selects objects or locations. They obtained data that they interpreted as evidence for attentional selection of objects from an internal spatially invariant representation. A. F. Kramer, T. A. Weber, and S. E. Watson question this interpretation on both theoretical and empirical grounds. First, the authors suggest that there are other interpretation of the Vecera and Farah data that are consistent with location-mediated selection of objects. Second, they provide data, using the displays employed by Vecera and Farah in conjunction with a postdisplay probe technique, that suggests that attention is directed to the locations of the target objects. The implications of the results for space and object-based attentional selection are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Constraints on the selection of auditory information.

Four experiments were conducted to determine whether or not (a) selection of auditory information may be guided separately by location and frequency channels and (b) auditory attention is allocated to spatial locations and frequency regions or to auditory objects (i.e., streams). In Experiment 1, listeners were to categorize tones by location or frequency. In Experiments 2A and 2B, target identification was examined as a function of its similarity to a precue. In Experiment 3, the time required to detect a target embedded within a sequence of distractor tones was examined. In all experiments, performance depended on both location and frequency information even if 1 of these features was completely irrelevant with respect to the task. Results indicate that selection of auditory information is accomplished by an attentional template normally defined by both location and frequency parameters. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition of Return to an Occluded Object Depends on Expectation.

Inhibition of return (IOR) is indexed by slower reaction times to targets presented at previously attended locations or objects. If a moving object is occluded, some studies find IOR, others do not. Four experiments examined whether this inconsistency hinges on the observer's expectation as to whether the object continues to exist at the end of its motion sequence. Results showed that observer expectation is a powerful determining factor: IOR occurs only if the observer expects the object to continue to exist. In contrast, if the object is not occluded, IOR occurs only if the object remains on view immediately before the target is presented. It was concluded that 2 factors, object continuity and observer expectation, mediate both location- and object-based IOR. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grouped arrays versus object-based representations: Reply to Kramer et al. (1997).

An important issue in attention research concerns the representational format from which attention selects. S. P. Vecera and M. J. Farah (see record 1994-32352-001) presented results that they argued demonstrated attentional selection from a spatially invariant object representation. In their comment, A. F. Kramer, T. A. Weber, and S. E. Watson (see record 84-18014) questioned the interpretation of these results, and they presented evidence consistent with selection from a grouped location-based representation. In this reply, the author argues that although an absence of spatial, or distance, effects may be ambiguous as to whether attention is selecting from an object-based representation or from a location-based representation, there are computational considerations that favor object-based selection in certain tasks. The author concludes with a discussion of how object-based and location-based representations might interact with one another, thereby providing a possible explanation of Kramer et al.'s results. Such an account may lead to an understanding of how multiple forms of attentional selection may coexist in the visual system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Organizational and spatial dynamics of attentional focusing in hierarchically structured objects.

Is the focusing of visual attention object-based, space-based, both, or neither? Attentional focusing latencies in hierarchically structured compound-letter objects were examined, orthogonally manipulating global size (larger vs. smaller) and organizational complexity (two-level structure vs. three-level structure). In a dynamic focusing task, participants successively identified the global and local letters in the same trial. Overall response latencies were generally longer for larger versus smaller global objects and for three-level versus two-level object structure, indicating that attentional focusing time increases both with the magnitude of change in attentional aperture size and with the number of traversed levels of object structure. Additional experiments showed that this pattern is unique to tasks that require dynamic attentional focusing. Taken together, the results support a hierarchical object-based-spatial model of attentional focusing. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Mechanisms of attentional priority.

When a single abrupt onset occurs in a multielement visual display, it captures attention, possibly by generating an attentional interrupt that designates onsets as being of high priority. In 3 experiments, the mechanisms subserving attentional priority setting were investigated. A total of 56 Ss searched for a prespecified target letter among multiple distractor letters, half of which had abrupt onsets and half of which did not. The target, when present, was equally often an onset element and a no-onset element. Several models for attentional priority, differing in how many onset elements have priority over no-onset elements, were assessed. The data support a model in which approximately 4 onset stimuli are processed before any no-onset stimuli are processed. Two attentional priority mechanisms are proposed: (1) queuing of a limited number of high-priority elements and (2) temporally modulated decay of attentional priority tags. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Kinetics of AMPA-type glutamate receptor channels in rat caudate-putamen neurones show a wide range of desensitization but distinct recovery characteristics

In 5 experiments the authors examine the role of object-based grouping on negative priming. The experiments used a letter-matching task with multiple letters presented in temporally separated prime and probe displays. On mismatch trials, distractor letters in primes were repeated as targets in probes, or distractor and target letters were completely different. Negative priming was shown by slowed responses when distractors were repeated as targets relative to when the stimuli differed. This occurred both when only letters were presented (Experiments 1 and 4) and when letters were surrounded by boxes (Experiment 5). Experiments 2, 3, and 4 showed that negative priming was affected by the grouping of target and distractor letters in prime displays. Negative priming was reduced when 1 of the distractor letters was placed in the target box and 1 was left outside the box; facilitatory priming was observed when both distractor letters appeared in the target box. The data were accounted for in terms of there being (a) object-based competition for visual selection, (b) inhibition of distractor objects that compete for selection with target objects, and (c) activation or inhibition of the identities of all component elements within target or distractor objects.     

Stroop and Garner effects in and out of Posner's beam: Reconciling two conceptions of selective attention.

Space- or object-based models, on the one hand, and structural-informational models, on the other hand, reflect conceptually distinct approaches to visual selective attention. In 3 studies, the authors contrasted these approaches by jointly applying prototypical routines prescribed in each approach. Following a space-based paradigm developed by M. I. Posner, participants were cued to attend to a certain spatial location, and performance at expected and unexpected locations was compared. Following a structural paradigm developed by W. R. Garner, the targets were color words printed in various colors, and the participants responded to either the color or the word component of the stimulus. Performance was poorer at unexpected than at expected locations. However, comparable amounts of Stroop and Garner interference affected performance at both expected and unexpected locations. It is suggested that the processes that govern (a) input selection from the visual field and (b) dimensional selection from the stimulus reflect fundamentally different systems of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Object-based perceptual grouping affects negative priming.

In 5 experiments the authors examine the role of object-based grouping on negative priming. The experiments used a letter-matching task with multiple letters presented in temporally separated prime and probe displays. On mismatch trials, distractor letters in primes were repeated as targets in probes, or distractor and target letters were completely different. Negative priming was shown by slowed responses when distractors were repeated as targets relative to when the stimuli differed. This occurred both when only letters were presented (Experiments 1 and 4) and when letters were surrounded by boxes (Experiment 5). Experiments 2, 3, and 4 showed that negative priming was affected by the grouping of target and distractor letters in prime displays. Negative priming was reduced when 1 of the distractor letters was placed in the target box and 1 was left outside the box; facilitatory priming was observed when both distractor letters appeared in the target box. The data were accounted for in terms of there being (a) object-based competition for visual selection, (b) inhibition of distractor objects that compete for selection with target objects, and (c) activation or inhibition of the identities of all component elements within target or distractor objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition of return: Dissociating attentional and oculomotor components.

Inhibition of return (IOR) describes a performance decrement for stimuli appearing at recently cued locations. Both attentional and motor processes have been implicated in the IOR effect. The present data reveal a double dissociation between the attentional and motor components of IOR whereby the motor-based component of IOR is present when the response is oculomotor, and the attention-based component of IOR is present when the response is manual. These 2 distinct components should be considered and studied separately, as well as in relation to each other, if a comprehensive theory of IOR is to be achieved. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Diazepam impairs temporal dynamics of visual attention.

The effect of benzodiazepines on attention has been the object of few investigations. Studies using the spatial cueing paradigm (Posner's paradigm) have reported inconsistent results, which are likely due to methodological and/or dose differences but suggest impaired disengagement of attention from the cue to the target. The authors investigated the effect of a benzodiazepine (diazepam) on attentional shifting in the temporal domain. The attentional blink effect refers to difficulties in detecting a target if it follows the identification of a previous target occurring within a temporal window of 200-400 ms. The authors assessed whether the duration of the attentional blink was affected by diazepam. Streams of 15 real-world scenes displaying a road were presented for 50 ms each. A city name (target) appeared at Serial Positions 2, 3, or 4 of each stream. A vehicle (probe) appeared at different intervals following the city name. In a dual-task condition, participants were asked to report the city name and whether a vehicle was present. In a control condition, participants had to report only the presence of a vehicle and ignore the city name. Thirty-six healthy volunteers were assigned to 3 groups (placebo, diazepam 0.1 mg/kg, or 0.3 mg/kg). Diazepam increased both the magnitude and duration of the attentional blink effect. Participants treated with a high dose of diazepam needed more than 600 ms to detect a vehicle following identification of the name. Results suggest that diazepam at a therapeutic dosage affects attentional shifting in the temporal domain and impairs dual-task performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences and similarities in the effects of cues and prompts.

A series of 6 experiments investigated the use of cues and prompts by younger and older adults. Cues provide useful information about an impending target, even though the information is not always valid. Prompts provide an instruction about what aspect of the target is to be responded to. The costs and benefits of cues were most consistent with models in which the attentional resources that are shifted in response to the cue were as large or larger in older adults as they were in younger adults. The results with both cues and prompts converged on the conclusion that the time course of processing and using a cue or prompt is the same in younger and older adults. The attentional resources tapped by these procedures cannot be the diminished processing resource to which many age differences in cognitive performance are attributed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial negative priming without mismatching: Comment on Park and Kanwisher (1994).

In spatial selective attention tasks, response time to locate a target is often longer when the target appears in a location that was recently occupied by an ignored distractor. It has been assumed that this "negative priming" effect occurs because internal representations associated with the distractor are inhibited during selection of the prime display target. In contrast, J. Park and N. Kanwisher (1994) have argued recently that spatial negative priming arises from mismatches between properties of the ignored distractor and subsequent probe target. In this article, 3 separate experiments demonstrate that negative priming can occur when the prime distractor and probe target are identical. Such effects are contrary to Park and Kanwisher's (1994) mismatching account of negative priming but congenial with an object-based inhibition mechanism of selection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)