Does attention affect visual feature integration?

Investigated whether (1) the integration of color and shape information is affected by attending to the stimulus location and (2) attending to a stimulus location enhances the perceptual representation of the stimulus or merely affects decision processes. In 3 experiments with 39 Ss (aged 16–38 yrs), Ss were briefly presented with colored letters. On most trials, Ss were precued to the stimulus location (valid cue); on some trials, a nonstimulus location was cued (invalid cue). Ss were less likely to combine colors and letter shapes incorrectly following a valid cue. The attentional facilitation afforded by the cue was not limited to feature integration but also affected the registration of features; however, when the amount of feature information was strictly controlled, attention still affected feature integration. It is suggested that orienting attention to the location of the cue affects the quality of the perceptual representation for features and their integration. (31 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Information transfer in iconic memory experiments.

To report letters from briefly exposed letter arrays, Ss must transfer information from a rapidly decaying trace (iconic memory) to more durable storage. In a partial-report paradigm, the proportion (P) of trials with a long cue delay relative to a short cue delay was systematically varied. Practiced Ss used the same transfer strategy independent of P. Data from a partial-report-plus-masking experiment were used to construct a computational model that accurately predicted partial- and whole-report performance with and without masks. Assumptions: Prior to a cue, Ss attend primarily to the middle row of a 3-row display, resulting in nonselective transfer. After the cue, they attend only to the cued row. Transfer rate is the product of iconic legibility (which depends on the time and retinal location) and attention allocation (which shifts after a cue). Cumulative transfer is limited by the capacity of durable storage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is Posner's "beam" the same as Treisman's "glue?" On the relation between visual orienting and feature integration theory.

In the present study we investigated whether the visually allocated "beam" studied by Posner and others is the same visual attentional resource that performs the role of feature integration in Treisman's model. Subjects were cued to attend to a certain spatial location by a visual cue, and performance at expected and unexpected stimulus locations was compared. Subjects searched for a target letter (R) with distractor letters that either could give rise to illusory conjunctions (PQ) or could not (PB). Results from three separate experiments showed that orienting attention in response to central cues (endogenous orienting) showed similar effects for both conjunction and feature search. However, when attention was oriented with peripheral visual cues (exogenous orienting), conjunction search showed larger effects of attention than did feature search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measuring and modeling the trajectory of visual spatial attention.

In a novel choice attention-gating paradigm, observers monitor a stream of 3x3 letter arrays until a tonal cue directs them to report 1 row. Analyses of the particular arrays from which reported letters are chosen and of the joint probabilities of reporting pairs of letters are used to derive a theory of attention dynamics. An attention window opens 0.15 s following a cue to attend to a location, remains open (minimally) 0.2 s, and admits information simultaneously from all the newly attended locations. The window dynamics are independent of the distance moved. The theory accounts for about 90% of the variance from the over 400 data points obtained from each of the observers in the 3 experiments reported here. With minor elaborations, it applies to all the principal paradigms used to study the dynamics of visual spatial attention. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Abrupt visual onsets and selective attention: Voluntary versus automatic allocation.

The hypothesis that abrupt visual onsets capture attention automatically, as suggested by S. Yantis and J. Jonides (see record 1985-19225-001), was tested in four experiments. A centrally located cue directed attention to one of several stimulus positions in preparation for the identification of a target letter embedded in an array of distractor letters. In all experiments, one stimulus (either the target or one of the distractors) had an abrupt onset; the remaining letters did not. The effectiveness of the cue was manipulated (varying either its duration or its predictive validity) to test whether abrupt onsets capture attention even when subjects are in a highly focused attentional state. Results showed that onsets do not necessarily capture attention in violation of an observer's intentions. A mechanism for partially automatic attentional capture by abrupt onset is proposed, and the diagnosticity of the intentionality criterion for automaticity is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contingent attentional capture by top-down control settings: Converging evidence from event-related potentials.

Theories of attentional control are divided over whether the capture of spatial attention depends primarily on stimulus salience or is contingent on attentional control settings induced by task demands. The authors addressed this issue using the N2-posterior- contralateral (N2pc) effect, a component of the event-related brain potential thought to reflect attentional allocation. They presented a cue display followed by a target display of 4 letters. Each display contained a green item and a red item. Some participants responded to the red letter and others to the green letter. Converging lines of evidence indicated that attention was captured by the cues with the same color as the target. First, these target-color cues produced a cuing validity effect on behavioral measures. Second, distractors appearing in the cued location produced larger compatibility effects. Third, the target-color cue produced a robust N2pc effect, similar in magnitude to the N2pc effect to the target itself. Furthermore, the target-color cue elicited a similar N2pc effect regardless of whether it competed with a simultaneous abrupt onset. The findings provide converging evidence for attentional capture contingent on top-down control settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional processing and the independence of color and orientation.

Judgments of the color and shape of a stimulus specified by a cue indicating its location demonstrate stochastic independence. Evidence for the independence of color and orientation was obtained when the cue followed stimulus offset immediately, the cue followed stimulus offset by 2 sec, and when either a central or peripheral precue focused attention on the cued stimulus at the time of its presentation. It appears that an object's color and orientation are represented independently even following the attentional focusing thought to support feature integration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning to read: The redundant cues approach.

Two experiments with 48 undergraduates in each investigated the effects of color coding sounds in Thai syllables on the acquisition of pronunciation responses and on transfer to syllables which were not color coded. The mere presence of color as a redundant cue had no significant effect on acquisition or transfer relative to a control group trained on uncoded syllables. When Ss were informed that color was a relevant cue and given pretraining which emphasized the color code, acquisition was facilitated, but transfer to uncoded syllables was impaired. When Ss were informed that color was a relevant cue and given pretraining which emphasized the shapes of the letters, acquisition was facilitated with no impairment on the transfer task. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the recognition of words with inverted letters.

Conducted 2 experiments in which 24 Ss were asked to identify words with all or some of their letters inverted. The experiments differed only in the explicitness of the instructions given to Ss. In some cases the letters appearing upside down were inverted as 1 unit, and in other cases they were inverted by letter. It was found that when all the letters were inverted, recognition time was faster for unit inversion. When just a few of the letters in the words were inverted, recognition time was shorter when the inversion was letter by letter rather than by unit. Data are consistent with a model that assumes that when the stimulus is homogeneously misoriented unit correction is applied, and when such homogeneity does not exist piecemeal correction is applied. (French abstract) (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Illusory conjunctions inside and outside the focus of attention.

This article addresses 2 questions that arise from the finding (e.g., W. Prinzmetal et al; see record 1986-26854-001) that visual scenes are first parsed into visual features: (a) the accumulation of location information about objects during their recognition and (b) the mechanism for the binding of the visual features. The first 2 experiments demonstrated that when 2 colored letters were presented outside the initial focus of attention, illusory conjunctions between the color of one letter and the shape of the other were formed only if the letters were less than 1° apart. Separation greater than 2° resulted in fewer conjunction errors than expected by chance. Experiments 3 and 4 showed that inside the spread of attention, illusory connections between the 2 letters can occur regardless of the distance between them. In addition, these experiments demonstrated that the span of attention can expand or shrink like a spotlight. The results suggest that features inside the focus of attention are integrated by an expandable focal attention mechanism that conjoins all features that appear inside its focus. Visual features outside the focus of attention may be registered with coarse location information prior to their integration. Alternatively, a quick and imprecise shift of attention to the periphery may lead to illusory conjunctions among adjacent stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Order of report and order of scanning in tachistoscopic recognition.

Presented horizontal rows of 8 letters across fixation to 6 university students. An instruction cue told Ss to report the letters either in a left-to-right or in a right-to-left sequence. There were 5 different temporal intervals between test stimulus and instruction cue and an ad lib condition, where the instruction cue was triggered by the Ss. With increasing interstimulus interval, the serial position curve for right-to-left report showed a significant transition from an initial superiority for letters to the right of fixation to a superiority for letters to the left of fixation. It is concluded that the asymmetry of the tachistoscopic serial position curve is due to the order of scanning the fading contents of a visual information store. (French summary) (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.     

Parafoveal identification asymmetry: interactive effects of shape and color

If two adjacent letters project to the parafoveal region of the retina, both accuracy and discriminability measures have revealed that a letter flanked to its foveal side is identified more accurately than a letter the same distance from the fovea that is flanked to its peripheral side. This parafoveal identification asymmetry is greater if the letters are dissimilar in shape than if they are similar. Color and brightness were introduced as variables in the present experiments. The identification asymmetry was greatest for dissimilar letters in different (complementary) colors. Although those colors differed also in brightness, two letters that were achromatic but merely different in brightness did not produce an asymmetry interaction with shape. Interletter separation was varied between .15 and 1.95 deg, and the pattern of results just described persisted across both distances. The synergistic interaction of shape relation and color relation in determining the amount of identification asymmetry suggests that color and shape affect perceptual processing at the same level.     

Shifting attention between global features and small details: an event-related potential study

In two experiments, large letters H or Z composed of small letters (also H or Z) were presented. Subjects had to make a two-choice motor response (e.g. H--left key, Z--right key). A cue presented 500 ms before the letter indicated which level (global or local) was relevant. In Experiment I, a third letter (T) sometimes appeared either at the cued or the non-cued level; in the former case, subjects had to shift their attention and to respond to stimulus features located at the non-cued level. The interference effect (RT delay in response to incongruent stimuli as compared to congruent ones) was larger when the local, rather than global, level was cued. A slow anterior negativity preceding globally-cued stimuli and shorter N1 and P2 ERP component latencies to these stimuli indicated better preparation for processing of global, as compared to local, stimulus features. The shift from local to global focus yielded a larger increase of RT, error rate, and of the P600 latency than the global-to-local shift. The P600 latency changes were parallel to those of RT. In Experiment II, the attentional shift was provoked by stimulus color red-colored letters meant that the cue was invalid, and thus, subjects had to respond to the non-cued level. Neither the interference nor the attentional shift demonstrated any asymmetry between the global and local levels. ERPs also did not differ substantially after local and global cues. In the condition demanding a shift of focus (invalid cue, incongruent letter), a positive deflection of the lateralized readiness potential indicated the activation of the wrong response channel. The large RT increment in this condition was not accompanied by an increase of the P600 latency. Two possible mechanisms of attentional shift may be proposed, the first related to perceptual processes (e.g. an additional visual search), and the second, to the competition between two response intentions.     

Attention, unpredictability, and reports of physical symptoms: Eliminating the benefits of predictability.

Conducted 3 experiments with 135 undergraduates to investigate the established finding from the unpredictability literature that exposure to unpredictable noise leads to reports of more severe physical symptoms than does exposure to predictable noise. In Exp I, Ss performed a reaction time (RT) task while they listened to loud bursts of either predictable or unpredictable noise. As expected, RTs were slower when the noise was unpredictable than when it was not. This finding suggests that more attention had been directed to the unpredictable than the predictable noise. In Exp II and III, Ss were exposed to either predictable or unpredictable noise and were instructed to attend to the noise or were given no instructions. In both cases, Ss not instructed to attend to the noise reported more severe symptoms when the noise was unpredictable than when it was not, thus replicating the previous finding. Of greater interest, however, was the fact that equating the amount of attention directed to the unpredictable and predictable noise (by asking Ss to attend to the noise) eliminated the apparent benefits of predictability. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of instructions on children's attention to stimulus components.

In 3 experiments, 5-, 8-, 9-, and 12-yr-olds were given a component-selection task with instructions to attend to one component or another or with no specific instructions. Ss at all age levels varied their attention to the nondominant component (color) in accord with instructions. Thus, children even as young as age 5 are capable of altering their manner of attention deployment. In another respect, however, data suggest a developmental change in the way children respond to varying task demands: Ss at 8 yrs of age and beyond, but not the 5-yr-olds, reduced their attention to the dominant component (shape) in response to instructions to concentrate on the nondominant component. During the early school years, children apparently develop a tendency to employ "attentional trading," withdrawing attention from a normally dominant stimulus component when it becomes advantageous to increase attention to another feature. Results are discussed as calling for modification of earlier hypotheses concerning development of attention. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neon colors illuminate reading units.

The effect of syllable-size reading units on neon color was investigated in 6 experiments. The stimuli consisted of 5- or 7-letter words or pseudowords with a syllable break either just before or just after the middle (target) letter. The target letter was overlaid with a plaid of red and green lines that gave it an ambiguous neon color. The letters preceding the target were overlaid with a monochromatic grid (red or green), and the letters following the target were overlaid with the other color. Ss were significantly more likely to judge the target as more similar to the color of other letters within its syllable than colors of letters outside that unit. The effect was shown not to be an artifact of guessing strategy or eye movements. Word structure determined by orthography and morphology affected neon colors, but no effect was found for purely phonological units. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new component of visual orienting: Implicit effects of peripheral information and subthreshold cues on covert attention.

Four experiments examined effects of peripheral cue stimuli on covert spatial attention. In Experiment 1 target stimuli were preceded by a pair of bilaterally presented cue letters. The relative location of the cues predicted target location (left or right), but participants were not informed of this. After a brief practice period, visual orienting was influenced by the letter cues. This implicit peripheral cuing effect was unrelated to participants' awareness of the cue-target relationship. Experiments 2 and 3 showed that visual orienting may occur independently of both perceptual awareness of the peripheral cue event itself and contingency awareness concerning the cue–target relation. Experiment 4 demonstrated that implicit peripheral cuing is qualitatively distinct from voluntary orienting. These findings are discussed in relation to work on spatial attention, implicit learning, and perception without awareness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alphabetic search: Comment on Klahr, Chase, and Lovelace (1983).

Response time (RT) curves were obtained from Ss who were instructed to search for following or preceding letters in the alphabet with respect to given stimulus letters. To describe the shape of these curves, D. Klahr et al (see record 1984-05777-001) proposed a search model. It was assumed that the alphabet was internally represented by a number of chunks of a few letters. Klahr et al assumed that serial searches occurred along 2 hierarchical levels: (1) a search for the correct chunk and (2) a search of the letters within the chunk. The Klahr et al model predicted an ascending sawtooth-shaped RT curve. However, according to the authors' analysis of the data, the RT curves did not show the expected sawtooth shapes. In order to find out whether the lack of empirical support for the model was an artifact of averaging the data, the experiment was replicated. It was found that individual RT curves did not show the shape characteristics that were predicted by the Klahr et al model either. The data supported the hypothesis that the access of letters was direct without any hierarchy, and that the retrieval of successive letters was determined by the variable associations between subsequent letters. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental changes in word recognition strategies

Attempted to determine when children develop adultlike strategies in word recognition and use the entire configuration as a basis for a response rather than individual letters. A total of 144 kindergartners, 1st-6th graders, and undergraduates were asked to choose an alternative which most resembled a stimulus trigram, quadrigram, or quingram. Ss could respond on the basis of individual letter position and overall word shape. There was a clear developmental trend such that, with increasing age, Ss were more likely to choose alternatives with the same shape as the stimulus. There was also a tendency to choose response alternatives with the same 1st letter as the stimulus through 4th grade, followed by a decreasing tendency to rely on the 1st letter starting with the 5th grade. Results are considered supportive of E. J. Gibson's (see record 1972-22179-001) hypothesis of a developmental change with increasing age and schooling in feature analysis and extraction. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)