Effects of attention on infants' preference for briefly exposed visual stimuli in the paired-comparison recognition-memory paradigm.

This study examined the effect of attention on 3- to 6-mo-olds' responses to briefly exposed visual stimuli. In Study 1, stimuli presented at 2.5 or 5.0 s resulted in a familiarity preference in a subsequent paired-comparison procedure. A novelty preference was found with 10.0- or 20.0-s exposure durations. In Study 2, a Sesame Street movie elicited heart-rate-defined attention phases and stimuli replaced Sesame Street during sustained attention, attention termination, or 5.0 s following attention termination. For 20 and 26-wk-olds, stimuli presented for 5.0 s during sustained attention resulted in a novelty preference similar to that found when exposure time was 20.0 s. The duration of stimulus exposure during sustained attention in the familiarization phase was positively correlated with the preference for the novel stimulus in the paired-comparison procedure. Thus, processing of briefly presented visual stimuli differs depending on the type of attention in which the infant is currently engaged. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A shape-contrast effect for briefly presented stimuli

When a suprathreshold visual stimulus is flashed for 60-300 ms and masked, though it is no longer visibly degraded, the perceived shape is vulnerable to distortion effects, especially when a 2nd shape is present. Specifically, when preceded by a flashed line, a briefly flashed circle appears to be an ellipse elongated perpendicular to the line. Given an appropriate stimulus onset asynchrony, this distortion is perceived when the 2 stimuli (approximately 4 degrees) are presented as far as 12 degrees apart but is not due to perception of apparent motion between the 2 stimuli. Additional pairs of shapes defined by taper and overall curvature also revealed similar nonlocal shape distortion effects. The test shapes always appeared to be more dissimilar to the priming shapes, a distortion termed a shape-contrast effect. Its properties are consistent with the response characteristics of the shape-tuned neurons in the inferotemporal cortex and may reveal the underlying dimensions of early shape encoding.     

Emerging attributes in monkey short-term memory.

Conducted 2 experiments to examine the role of recency information and stimulus novelty and familiarity in delayed-matching-to-sample (DMTS) performance. Five female 5–8 yr old macaques (one of which was not included in Exp II) were tested on DMTS problems in which the correct and incorrect choice stimuli were both familiar, both relatively novel, or different in familiarity. Initially, novelty and familiarity exerted their influence as preferences (familiar stimuli were preferred). As more training was given, however, novelty and familiarity began to act as discriminative attributes. For example, Ss came to use the fact that the to-be-remembered stimulus was relatively novel to reject alternative choice stimuli that were more familiar. Theories of animal memory based on a single memory attribute cannot address these results. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The shape of threat: Simple geometric forms evoke rapid and sustained capture of attention.

Previous work has indicated that simple geometric shapes underlying facial expressions are capable of conveying emotional meaning. Specifically, a series of studies found that a simple shape, a downward-pointing "V," which is similar to the geometric configuration of the face in angry expressions, is perceived as threatening. A parallel line of research has determined that threatening stimuli more readily capture attention. In five experiments, the authors sought to determine whether this preferential processing was also present for the simple geometric form of a downward-pointing "V." Using a visual search paradigm, across these experiments the authors found that, when embedded in a field of other shapes, downward-pointing V's were detected faster and, in some cases, more accurately than identical shapes pointing upward. These findings indicate that the meaning of threat can be conveyed rapidly with minimal stimulus detail. In addition, in some cases, during trials of homogeneous fields of stimuli, fields of downward-pointing V's led to slower response times, suggesting that this shape's ability to capture attention may also extend to difficulty in disengaging attention as well. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search as a function of type of prior experience with target and distractor.

In a visual search task, participants identified the presence of a unique shape against a background of homogeneous distractors. Types of prior experience with the target, the distractor, or both were examined. In 2 experiments, a preexposure (PE) phase was followed by a test phase. The test display consisted of a target that was either target or distractor in PE or novel. Distractors were either targets or distractors in PE or novel. Reaction time was fastest for novel targets with familiar distractors, irrespective of the source of familiarity, and slowest for novel targets with novel distractors. Results are discussed in terms of attentional explanations of latent inhibition (LI) and perceptual learning and of visual search phenomena, such as novel popout. LI, previously attributed only to a deficit in the stimulus preexposed group, may also be due to enhanced performance in the nonpreexposed group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of familiarity and unitization on new-association priming.

The role of familiarity and stimulus unitization was examined for nonverbal associations. Implicit memory was tested using a color-naming task. In 2 experiments spatially separated words, novel shapes, or nonwords and colors were presented, and the encoding instructions encouraged their unitization. New-association priming occurred between words and colors but not between abstract shapes and colors or between nonwords and colors. The results suggest that new-association priming occurs for familiar stimuli that are not physically integrated. However, when the stimuli are neither familiar nor unitized, new-association priming does not occur. It is possible that during encoding, memory representations are activated. If the stimuli are neither familiar nor unitized, then these processes must be carried out at study at the expense of learning of the associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing of contour closure by baboons (Papio papio).

This study investigated the Gestalt law of closure in baboons. Using a computer-controlled self-testing procedure, we trained baboons (Papio papio) to discriminate open versus closed shapes presented on a touch screen with a two-alternative forced choice procedure. Ten baboons (OPEN + group) were trained with the open shapes serving as the positive stimulus (S+), and nine others (CLOSE + group) were trained with the closed shape serving as S+. The OPEN + group obtained higher discrimination performance than the CLOSE + group (Exp 1), but its scores declined when new line segments were added to the stimuli (Exp 2) and after smoothing the end points of the open shapes (Exp 3). The CLOSE + group was less affected by the above manipulations of local stimulus dimension, but its performance was disrupted when the collinearity end points was reduced (Exp 3). Use of a visual search task revealed that the search for an open shape among closed distractors was less attention demanding in baboons than the search for a closed shape among open ones (Exp 4). It is concluded that (1) end lines rather than closeness per se are perceptual primitives for the open versus closed discrimination in baboons, and (2) the relative emphasis on local or configural cues when processing contour closure depends on experiential factors in baboons and is thus subject to interindividual variations. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Familiarity and novelty preferences in infant recognition memory: Implications for information processing.

Investigated the suggestion that young infants show a preference for familiar stimuli that is supplanted by a preference for novel stimuli as they get older and the act of recognition becomes commonplace. In Study 1, 84 Ss (3.5, 4.5, and 6.5 mo old) were tested for visual recognition memory of shapes, using the paired comparison procedure. The 3.5-mo-olds showed a strong preference for the familiar, whereas the older Ss preferred the novel stimulus. In Study 2 with 72 3.5- and 6.5-mo-old Ss, these shifts were found to depend more on familiarization time than on age. Ss of both ages showed a preference for the familiar stimulus after limited exposure to it but shifted to a preference for the novel stimulus after more extended exposure. It is concluded that regardless of age, infants prefer to look at that which is familiar as they begin to process a stimulus; once processing becomes more advanced, their preference shifts to the novel. Findings are therefore contrary to the developmental view investigated. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nonspecific effects of exposure on stimuli that cannot be recognized.

The repeated exposure of unmasked irregular geometric shapes for very brief durations (1 or 2 ms) has been shown to generate preferences as well as judgments of familiarity for the previously exposed shapes. At the same time these stimuli are not recognized as having been presented. Such exposure also leads to judgments of brightness and darkness independent of stimulus intensity, and it is dependent on the use of unmasked stimuli. This effect is nonspecific, in contrast to stimulus-specific effects with masked stimuli, and it is not restricted to affective judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual Differences in the Pattern of Habituation at 5 and 10 Months of Age.

Individual differences in pattern of habituation in fixation time and cardiac change to visual and auditory stimuli are described. Nearly half of the longitudinal sample at 5 months and almost 90% at 10 months did not display a monotonically decreasing habituation pattern over trials, a result that challenges the use of simple indices of response decline as measures of rate of information processing. A positive response to a novel stimulus at 5 and 10 months was observed only if an obvious peak response followed by a decline occurred during familiarization and (for 5-month-old subjects only) if the peak/decline occurred shortly before the introduction of the novel stimulus. Relative to 5 months, habituation patterns at 10 months were flatter and more irregular, and individual differences did not revolve around a few prototypical patterns. No evidence was observed for individual stability in type of habituation pattern across modality within an age or within modality across age, nor were there many correlates between pattern and demographic characteristics of the subjects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Global and local processing in humans (Homo sapiens) and chimpanzees (Pan troglodytes): Use of a visual search task with compound stimuli.

This research assessed the visual processing of the global and local stimulus features in humans and chimpanzees. In Experiment 1, participants were tested with compound stimuli presented in a visual search task. There was an advantage to process the global stimulus level in humans but not in chimpanzees. The global size and the density of the local elements were manipulated in Experiment 2. Humans showed an overall advantage for processing the global shape. Chimpanzees showed an advantage for processing the local shape in the low-density condition but showed no advantage in the dense conditions. In Experiment 3, chimpanzees showed a global advantage when line segments connected the local elements and a local one when the lines were removed. Together, these results suggest a phylogenetic trend in the way compound stimuli are processed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The guidance of eye movements during active visual search

An analysis of monkey eye movements in classic conjunction and feature search tasks was made. The task was to find and fixate a target in an array of stimuli. Saccades targeted stimuli accurately (red and green bars, 1.25 x 0.25 degrees), landing most of the time within 1.0 degree of the stimulus center and rarely in blank areas far from any stimulus. Monkeys used target color, but not orientation, to selectively guide search. Saccades moved the point of fixation on the average just beyond the area that could be examined by focal attentive mechanisms during the current fixation, as described in a previous paper (Motter BC, Belky EJ. The zone of focal attention during active visual search. Vis Res 1998;38:1007-22). This distance scales with the density of relevant stimuli in the scene. The saccade targeting data suggest that the locations of items of a particular color, but apparently not of a particular orientation, are available outside the region of focal attention. Color feature selection can apparently block the distracting effects of color unique distractors during search.     

Effects of stimulus and environmental familiarity on visual imprinting in newly hatched ducklings.

Reports 2 experiments with 18 Khaki Campbell ducklings 17 hrs old which attempted to determine whether the development of familiarity with a particular source of visual stimulation was a sufficient condition for Ss to restrict their emission of filial behavior to that source only and begin to react fearfully to others. The reaction of Ss to familiar and novel imprinting stimuli in familiar and unfamiliar environments were assessed. Results indicate that familiarity alone is not sufficient for the emergence of fear. It is suggested that consideration of maturational as well as experiential factors is necessary for a full understanding of the Ss' reactions during imprinting. (28 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cross-modal equivalence in early infancy: Auditory–visual intensity matching.

To examine the hypothesis that young infants ignore differences between lights and sounds and instead respond to auditory and visual stimuli as more or less similar depending on their intensity, a cardiac habituation/dishabituation method with a test for stimulus generalization was employed. In 2 experiments, a total of 40 3-wk-old Ss were repeatedly presented with white-light followed by white-noise stimuli of different intensities. A U-shaped relationship between magnitude of cardiac response (CR) and loudness was found. In view of previous findings that without prior visual stimulation a monotonic increase in CR to the same range of auditory stimuli results, this finding of a significant quadratic relationship with loudness suggests that Ss were responding to the auditory stimuli in terms of their similarity to the previously presented visual stimulus. A separate group of 14 infants presented with a more intense visual stimulus exhibited a shift in the intensity at which a minimal CR occurred. Results of a study with 31 adults did not show any systematic relationship between CR and loudness, indicating that unlike infants, adults do not spontaneously make cross-modal matches of intensity. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feature analysis in early vision: Evidence from search asymmetries.

A series of search experiments tested detection of targets distinguished from the distractors by differences on a single dimension. Our aim was to use the pattern of search latencies to infer which features are coded automatically in early vision. For each of 12 different dimensions, one or more pairs of contrasting stimuli were tested. Each member of a pair played the role of target in one condition and the role of distractor in the other condition. Targets defined by larger values on the quantitative dimensions of length, number, and contrast, by line curvature, by misaligned orientation, and by values that deviated from a standard or prototypical color or shape were detected easily, whereas targets defined by smaller values on the quantitative dimensions, by straightness, by frame-aligned orientation, and by prototypical colors or shapes required slow and apparently serial search. We interpret the results as evidence that focused attention to single items or to groups is required to reduce background activity when the Weber fraction distinguishing the pooled feature activity with displays containing a target and with displays containing only distractors is too small to allow reliable discrimination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multisensory prior entry.

Despite 2 centuries of research, the question of whether attending to a sensory modality speeds the perception of stimuli in that modality has yet to be resolved. The authors highlight weaknesses inherent in this previous research and report the results of 4 experiments in which a novel methodology was used to investigate the effects on temporal order judgments (TOJs) of attending to a particular sensory modality or spatial location. Participants were presented with pairs of visual and tactile stimuli from the left and/or right at varying stimulus onset asynchronies and were required to make unspeeded TOJs regarding which stimulus appeared first. The results provide the strongest evidence to date for the existence of multisensory prior entry and support previous claims for attentional biases toward the visual modality and toward the right side of space. These findings have important implications for studies in many areas of human and animal cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detecting targets in letter and non-letter arrays.

Three experiments with 48 right-handed undergraduates examined the difference between the processing of letter and nonletter arrays using visual search. Results show that (1) letters were processed differently from other shapes; specifically, detection latencies were relatively short for the ends of letter arrays and increased left to right yielding a sloping M-shaped function, whereas the function for nonletter arrays was U-shaped; (2) this result was not restricted to any one nonletter character set, nor is visual familiarity or nameability crucial; and (3) digits produced results comparable to letters. Mechanisms common to word and number processing are advanced to account for this latter finding. The basic letter–shape contrast shows that the letter position function is constrained by processing strategy, not by structural limitations. (French abstract) (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotion at the expense of cognition: Psychopathic individuals outperform controls on an operant response task.

The impact of emotional stimuli on a simple motor response task in individuals with psychopathy and comparison individuals was investigated. Psychopathy was assessed using the Psychopathy Checklist Revised (Hare, 1991). Participants were presented with the Emotional Interrupt Task, in which they responded with left and right button presses to shapes that were temporally bracketed by positive, negative, and neutral visual images taken from the International Affective Picture System. The comparison group showed increased response latencies if the shape was temporally bracketed by either a positive or negative emotional stimulus relative to a neutral stimulus. Individuals with psychopathy did not show this modulation of reaction time for either positive or negative emotional stimuli. Results are discussed with reference to current models regarding the modulation of attention by emotion and the emotional impairment seen in individuals with psychopathy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What visual information do children and adults consider while switching between tasks? Eye-tracking investigation of cognitive flexibility development.

This study investigated the visual information that children and adults consider while switching or maintaining object-matching rules. Eye movements of 5- and 6-year-old children and adults were collected with two versions of the Advanced Dimensional Change Card Sort, which requires switching between shape- and color-matching rules. In addition to a traditional integrated version with bidimensional objects (e.g., a blue bear), participants were tested on a dissociated version with pairs of unidimensional objects as stimuli (e.g., a noncolored bear beside a blue patch) so that fixations on the relevant and irrelevant dimensions of the stimuli could be distinguished. The fixation times were differentially distributed depending on whether children had to switch or maintain matching rules. Trial type differences in fixation times were primarily observed for the cues and the relevant and irrelevant dimensions of the stimuli, whereas responses options were seldom fixated even by the youngest children. In addition, the shape modality of the stimulus was more fixated than the color modality whether or not shape was relevant. Finally, the fixation patterns were modulated by age. These results suggest that switch costs are more related to selection of the relevant dimension on the stimulus than to response selection and point to age-related differences in strategies underlying flexible behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Limitations on the parallel guidance of visual search: Color?×?Color and Orientation?×?Orientation conjunctions.

In visual search for a conjunction it is much more difficult to search for the conjunction of 2 colors or 2 orientations than for Color?×?Orientation or Color?×?Shape conjunctions. The result is not limited to particular colors or shapes. Two colors cannot occupy the same spatial location in Color?×?Color searches. However, Exps 6 and 7 show that Color?×?Shape searches remain efficient even if the color and shape are spatially separated. Our guided search model suggests that in searches for Color?×?Shape a parallel color module can guide attention toward the correct color, whereas the shape module guides attention toward the correct shape. Together these 2 sources of guidance lead attention to the target. However, if a target is red and green among red–blue and green–blue distractors, it is not possible to guide search independently toward red items and green items or away from all blue items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)