Dominance of configural properties in visual form perception

Perceptual relations between configural and component properties were examined in three experiments. The pattern of performance in discrimination and classification tasks with a set of four lines that varied in curvature (Experiment 1) was compared with the pattern of performance in these tasks with sets of configuration defined on spatial relations among these lines. The configurations in the latter sets varied in their component properties (“curvature”) as well as in their configural properties (“closure” in Experiment 2 and “parallelism” in Experiment 3). The results indicated that discrimination and classification performance with the configurations was dominated by their configural properties, regardless of the discriminability of their component properties. The implications of these results for the role of configural properties in form perception are discussed.     

Individual differences in infant fixation duration: Dominance of global versus local stimulus properties

In three experiments, the dominance of global versus local visual properties was investigated in 4-month-old infants as a function of individual differences in fixation duration (i.e., “long-” versus “short-looking” infants). Dominance was assessed through paired-comparison discrimination tasks in which global and local visual properties were placed in competition with one another for infants' attention. Familiarization time was varied parametrically across experiments. Short-looking infants showed responses consistent with a global-to-local sequence of processing: dominance for the global attribute was supplanted by dominance for the local attribute as familiarization was extended. Long-looking infants, however, did not show dominance for either visual property until after considerable familiarization. When dominance was observed for this group, it was for the local visual attribute. These findings are in accord with previous observations that long-looking infants process visual information more slowly than short-looking infants, but further suggest that there may be qualitative differences in the manner in which the two groups of infants attend to the properties of visual stimuli. Links between this finding and the long-term predictive validity of fixation duration are discussed.     

The role of local and global properties in comparison of analogical visual scenes

Love, Rouder, and Wisniewski (1999) obtained interesting results showing that, in a same/different task on abstract visual scenes, subjects were able to process global properties quickly, even before local properties were identified. Our aim in this work is to explore more fully the complex relationships that exist between local processing and global processing. In our first experiment, we tested the robustness and generality of these global and local effects by using another, very different kind of local element. We showed that the global effects remain strong even when the local elements are neither conventional nor easily discriminable. In the second experiment, we showed that there exists an intermediate level of similarity between purely local and purely global similarity. Furthermore, we found that even when a stronger form of local dissimilarity is manipulated (through the introduction of different local elements), global effects were still observed. We conclude with a discussion of the respective roles of global and local properties in light of our findings.     

Local and global aspects of biological motion perception in children born at very low birth weight

Biological motion perception can be assessed using a variety of tasks. In the present study, 8- to 11-year-old children born prematurely at very low birth weight (<1500 g) and matched, full-term controls completed tasks that required the extraction of local motion cues, the ability to perceptually group these cues to extract information about body structure, and the ability to carry out higher order processes required for action recognition and person identification. Preterm children exhibited difficulties in all 4 aspects of biological motion perception. However, intercorrelations between test scores were weak in both full-term and preterm children—a finding that supports the view that these processes are relatively independent. Preterm children also displayed more autistic-like traits than full-term peers. In preterm (but not full-term) children, these traits were negatively correlated with performance in the task requiring structure-from-motion processing, r(30) = ?.36, p < .05), but positively correlated with the ability to extract identity, r(30) = .45, p < .05). These findings extend previous reports of vulnerability in systems involved in processing dynamic cues in preterm children and suggest that a core deficit in social perception/cognition may contribute to the development of the social and behavioral difficulties even in members of this population who are functioning within the normal range intellectually. The results could inform the development of screening, diagnostic, and intervention tools.     

Local and global orientation in visual search

Six experiments investigated the role of global (shape) and local (contour) orientation in visual search for an orientation target. Experiment 1 demonstrated thatsearch for a conjunction of local contours with a distinct global orientation was less efficient than search for a target featurally distinct in terms of both global and local contour orientation. However, Experiments 2 and 4 demonstrated that the presence of a unique line contour was neither sufficient nor necessary to allow efficient search. Experiment 5 found thatsearch for a local orientation difference was strongly impeded by irrelevant variation in global orientation, arguing for a preeminent role for global orientation. Finally, Experiment 6 demonstrated that the orientation search asymmetry holds for the global orientation of stimuli. Taken together, the results are consistent with visual search processes guided predominately by a representation of global orientation.     

Biological motion preference in humans at birth: role of dynamic and configural properties

The present study addresses the hypothesis that detection of biological motion is an intrinsic capacity of the visual system guided by a non-species-specific predisposition for the pattern of vertebrate movement and investigates the role of global vs. local information in biological motion detection. Two-day-old babies exposed to a biological motion point-light display (depicting a walking hen) and a non-biological motion display (a rotating rigid object) preferentially looked at the biological display (Experiment 1). A new group of newborns showed themselves to be capable of discriminating, following habituation, a biological motion display from a spatially scrambled version of it (Experiment 2). However, a third group of newborns, at their first exposure to such displays, did not show any preference between them (Experiment 3). Results confirm and extend previous comparative and developmental data, supporting an inborn predisposition to attend to biological motion in humans. This ability is presumably part of an evolutionarily ancient and non-species-specific system predisposing animals to preferentially attend to other animals.     

Local and global factors of similarity in visual search

Effects of the similarity between target and distractors in a visual search task were investigated in several experiments. Both familiar (numerals and letters) and unfamiliar (connected figures in a 5 × 5 matrix) stimuli were used. The observer had to report on the presence or absence of a target among a variable number of homogeneous distractors as fast and as accurately as possible. It was found that physical difference had the same clear effect on processing time far familiar and for unfamiliar stimuli: processing time decreased monotonically with increasing physical difference. Distractors unrelated to the target and those related to the target by a simple transformation (180° rotation, horizontal or vertical reflection) were also compared, while the physical difference was kept constant. For familiar stimuli, transformational relatedness increased processing time in comparison with that fort unrelated stimulus pairs. It was further shown in a scaling experiment that this effect could be accounted for by the amount of perceived similarity of the target-distractor pairs. For unfamiliar stimuli, transformational relatedness did have a smaller and less pronounced effect. Various comparable unrelated distractors resulted in a full range of processing times. Results from a similarity scaling experiment correlated well with the outcome of the experiments with unfamiliar stimuli. These results are interpreted in terms of an underlying continuum of perceived similarity as the basis of the speed of visual search, rather than a dichotomy of parallel versus serial processing.     

Dominance and typicality norms for properties: Convergent and discriminant validity

Sensory properties of verbally depicted items, such as those of color or shape, were indexed for dominance (frequency of output) and typicality (perceptual “goodness”). Participants (total N=193) served in one of four conditions. The most dominant property response was computed for 105 nouns by one group. A second group rated these properties for typicality, relative to a constituent property (i.e., given one’s idea of yellow, how typically “yellow” are the following items: butter, canary, daffodil, ...). A third group produced as many properties as possible for each of 65 nouns. Dominance was computed for all 459 properties so produced. The last group rated these 459 properties for typicality relative to the parent noun (i.e., Given your image of an apple, how typically round is it? How typically soft is it? etc.). A multimethod-multitrait analysis indicated that both typicality and dominance were reliable, and that both exhibited convergent and discriminant validity. Typicality measured relative to an ideal property exhibited greater discriminant validity from dominance than when measured relative to the parent noun. Selected uses of these norms in studies of semantic memory, metaphor judgment, and concept identification were discussed.     

Processing dominance of global and local information in visual patterns

The processing dominance of global and local levels of visual patterns was studied using two tasks: speeded classification and identification. Stimuli were presented with spatial certainty and controlled eccentricity. The results with both procedures showed global advantage: RTs to global level were faster than those to local level. In the same way, the interference effect was bidirectional between the global and local levels, the amount of interference being larger from the global level to the local one than vice versa.     

Boundaries of semantic distraction: Dominance and lexicality act at retrieval

Three experiments investigated memory for semantic information with the goal of determining boundary conditions for the manifestation of semantic auditory distraction. Irrelevant speech disrupted the free recall of semantic category- exemplars to an equal degree regardless of whether the speech coincided with presentation or test phases of the task (Experiment 1), and this occurred regardless of whether it comprised random words or coherent sentences (Experiment 2). The effects of background speech were greater when the irrelevant speech was semantically related to the to-be-remembered material, but only when the irrelevant words were high in output dominance (Experiment 3). The implications of these findings in relation to the processing of task material and the processing of background speech are discussed.     

Intermodal perception at birth: Intersensory redundancy guides newborn infants’ learning of arbitrary auditory−visual pairings

In this study the ability of newborn infants to learn arbitrary auditory–visual associations in the absence versus presence of amodal (redundant) and contingent information was investigated. In the auditory-noncontingent condition 2-day-old infants were familiarized to two alternating visual stimuli (differing in colour and orientation), each accompanied by its ‘own’ sound: when the visual stimulus was presented the sound was continuously presented, independently of whether the infant looked at the visual stimulus. In the auditory-contingent condition the auditory stimulus was presented only when the infant looked at the visual stimulus: thus, presentation of the sound was contingent upon infant looking. On the post-familiarization test trials attention recovered strongly to a novel auditory–visual combination in the auditory-contingent condition, but remained low, and indistinguishable from attention to the familiar combination, in the auditory-noncontingent condition. These findings are a clear demonstration that newborn infants’ learning of arbitrary auditory–visual associations is constrained and guided by the presence of redundant (amodal) contingent information. The findings give strong support to Bahrick’s theory of early intermodal perception.     

Determinants of attention to local and global features of visual forms

This article deals with the problem of how attention is distributed to different levels of detail (global, local) in visual scenes. Six experiments explore the effect of a previous level of processing on current processing. The contention that processing at a given level of detail biases the distribution of attention so that more is allocated to that level for future processing is supported by the presence in the data of a robust level-readiness effect, whereby processing is faster at a given level if previous processing has been at that level. The level-readiness effect occurs regardless of the conspicuity of features at the various levels. Conflict between levels seems to depend on the imbalance of conspicuity and attention allocation between levels, with the more conspicuous or attended-to-level interfering more. A model of two-state attention switching similar to that of Sperling and Melchnor (1978) is proposed to explain these data. the final experiment confirmed the somewhat unusual prediction of this model that sometimes processing under focusing-attention conditions can be slower than that under divided-attention conditions.     

The growth of the effective visual field from birth to seven weeks

Visual orientation toward a peripheral stimulus by newborns and 7-week-old infants was examined with both a central stimulus present and absent. The presence of the central stimulus narrowed but did not eliminate peripheral responding. No age change was found when a central stimulus was present. However, older infants exhibited greater peripheral responding than newborns when the central stimulus was absent. The neonate appears to exercise internal control over his sampling of the stimulus array rather than being passively captured by it.     

The effect of spatial-frequency filtering on the visual processing of global structure

In three experiments we measured reaction times (RTs) and error rates in identifying the global structure of spatially filtered stimuli whose spatial-frequency content was selected by means of three types of 2-D isotropic filters (Butterworth of order 2, Butterworth of order 10, and a filters with total or partial Gaussian spectral profile). In each experiment, low-pass (LP), bandpass (BP), and high-pass (HP) filtered stimuli, with nine centre or cut-off spatial frequencies, were used. Irrespective of the type of filter, the experimental results showed that: (a) RTs to stimuli with low spatial frequencies were shorter than those to stimuli with medium or high spatial frequencies, (b) RTs to LP filtered stimuli were nearly constant, but they increased in a nonmonotonic way with the filter centre spatial frequency in BP filtered stimuli and with the filter cut-off frequency in HP filtered stimuli, and (c) the identification of the global pattern occurred with all visible stimuli used, including BP and HP images without low spatial frequencies. To remove the possible influence of the energy, a fourth experiment was conducted with Gaussian filtered stimuli of equal contrast power (c(rms) = 0.065). Similar results to those described above were found for stimuli with spatial-frequency content higher than 2 cycles deg(-1). A model of isotropic first-order visual channels collecting the stimulus spectral energy in all orientations explains the RT data. A subsequent second-order nonlinear amplitude demodulation process, applied to the output of the most energetic first-order channel, could explain the perception of global structure of each spatially filtered stimulus, including images lacking low spatial frequencies.