Feeling textures through a probe: effects of probe and surface geometry and exploratory factors

Vibratory roughness perception occurs when people feel a surface with a rigid probe. Accordingly, perceived roughness should reflect probe and surface geometry, exploratory speed, and force. Experiments 1 and 2 compared magnitude estimation of roughness with the bare finger and two types of probes, one designed to eliminate force moments, under the subject's active control. Experiments 3 and 4 varied speed under passive control. Log magnitude was consistently a quadratic function of log spacing between elements in the surface. The location of the function's peak was related to the drop point--that is, the spacing at which the probe can just drop between elements--which is affected by probe tip diameter, element height, and speed. Other parameters of the quadratic were affected by probe type and speed.     

Children's working-memory processes: a response-timing analysis

Recall response durations were used to clarify processing in working-memory tasks. Experiment 1 examined children's performance in reading span, a task in which sentences were processed and the final word of each sentence was retained for subsequent recall. Experiment 2 examined the development of listening-, counting-, and digit-span task performance. Responses were much longer in the reading-and listening-span tasks than in the other span tasks, suggesting that participants in sentence-based span tasks take time to retrieve the semantic or linguistic structure as cues to recall of the sentence-final words. Response durations in working-memory tasks helped to predict academic skill and achievement, largely separate from the contributions of the memory spans themselves. Response durations thus are important in the interpretation of span task performance.     

A case of collective responsibility: who else was to blame for the Columbine high school shootings?

Two studies examined perceptions of collective responsibility for the April 20, 1999, shootings at Columbine High School in Littleton, Colorado. Collective responsibility refers to the perception that others, besides the wrongdoers themselves, are responsible for the event. In Study 1, the authors assessed perceptions of the shooters' parents and their peer group (the Trenchcoat Mafia), whereas Study 2 tested perceptions of collective responsibility across a range of groups. In both studies, perceptions of a target group's entitativity predicted judgments of collective responsibility. This relationship was mediated by two situational construals that justify applying collective responsibility: responsibility by commission (encouraging or facilitating the event) and responsibility by omission (failing to prevent the event). Study 2 also determined that perceptions of authority predicted judgments of collective responsibility for the Columbine shootings and was mediated by inferences of omission. Future directions in collective responsibility research are discussed.     

Developmental prosopagnosia: a study of three patients

We studied perception in three patients with prosopagnosia of childhood onset. All had trouble with other 'within-category' judgments. All were deficient on face matching tests and severely impaired on tests of perception of the spatial relations of facial features and abstract designs, indicating a deficit in the encoding of coordinate relationships, similar to adult-onset prosopagnosia with lesions of the fusiform face area. Two had difficulty perceiving feature colour, which correlated with reduced luminance sensitivity. In contrast to adult-onset patients, saturation discrimination was spared in two and spatial resolution impaired in two. Curvature discrimination was relatively spared. Contrast sensitivity showed variable reductions at different spatial frequencies. We conclude that developmental prosopagnosia is similar to the adult-onset form in encoding deficits for the spatial arrangement of facial elements. Deficits in luminance perception and spatial resolution are more associated with defective encoding for basic object-level recognition, as shown on tests of object and spatial perception.     

What is a visual object? Evidence from target merging in multiple object tracking

The notion that visual attention can operate over visual objects in addition to spatial locations has recently received much empirical support, but there has been relatively little empirical consideration of what can count as an 'object' in the first place. We have investigated this question in the context of the multiple object tracking paradigm, in which subjects must track a number of independently and unpredictably moving identical items in a field of identical distractors. What types of feature clusters can be tracked in this manner? In other words, what counts as an 'object' in this task? We investigated this question with a technique we call target merging: we alter tracking displays so that distinct target and distractor locations appear perceptually to be parts of the same object by merging pairs of items (one target with one distractor) in various ways - for example, by connecting item locations with a simple line segment, by drawing the convex hull of the two items, and so forth. The data show that target merging makes the tracking task far more difficult to varying degrees depending on exactly how the items are merged. The effect is perceptually salient, involving in some conditions a total destruction of subjects' capacity to track multiple items. These studies provide strong evidence for the object-based nature of tracking, confirming that in some contexts attention must be allocated to objects rather than arbitrary collections of features. In addition, the results begin to reveal the types of spatially organized scene components that can be independently attended as a function of properties such as connectedness, part structure, and other types of perceptual grouping.     

Effects of accelerated reading rate on processing words' syntactic functions by normal and dyslexic readers: event related potentials evidence.

In the present study, the authors examined differences in brain activity, as measured by amplitudes and latencies of event related potentials (ERP) components, in Hebrew-speaking adult dyslexic and normal readers when processing sentence components with different grammatical functions. Participants were 20 dyslexic and 20 normally reading male college students aged 18-27 years. The authors examined the processing of normal word strings in word-by-word reading of sentences having subject-verb-object (SVO) syntactic structure in self- and fast-paced conditions. Data revealed that in both reading conditions, the N100 and P300 ERP components were sensitive to internal processes such as recognition of words' grammatical functions. However, the results revealed that fast-paced reading rate might affect this process, as was reflected in the systematic changes of amplitudes and latencies of both ERP components. In accelerated reading, a significant decrease of latencies and increase of amplitudes in dyslexics were shown. It was also found that influence of fast-paced reading rate was realized in the full usage of the word-order strategy in sentence processing. In turn, this fact confirmed the hypothesis concerning a syntactic processing "weakness" in dyslexia.     

Indexing individual objects in infant working memory

Currently there are disputes in the infancy literature concerning when infants are first able to individuate physical objects by their features or properties. This issue has taken on new significance following claims that individuation by feature is linked to the emergence of object kind concepts toward the end of the first year. Needham (2001, this issue) presents evidence that infants as young as 4.5 months old can individuate objects by feature. We locate this controversy within the framework of brain mechanisms that index or track individual objects, drawing upon theories of attention and working memory developed in the study of adults. We find that Needham's work contributes to two issues: categorization and the effect of object history on the individuation of objects in a complex display.     

Test-retest reliability of the Advanced Psychodiagnostic Interpretation (API) scoring system for the Bender Gestalt in chronic schizophrenics

This study assesses the test-retest reliability of the revised Advanced Psychodiagnostic Interpretation (API) scoring system for the Bender Gestalt Test (BGT). The API system identifies 207 possible distortions in a BGT protocol. Test-retest reliability for 40 schizophrenic patients tested twice with a mean interval of 6.4 years (SD=3.8 years) was good, ranging from .71 to .80. Further reliability and validity studies are needed to further demonstrate the effectiveness of the system.     

Who's Being Served? "Self-Serving" Attributions in Social Hierarchies

Making external attributions for negative events, though often considered “self-serving,” also implies that the attributor is not in control of critical resources. We hypothesized that making external attributions for negative events will lead to impressions of powerlessness. Because individuals in high-status roles are expected to have power and control, external attributions may violate these role expectations; thus, we further hypothesized that status would moderate the relationship between attributions and interpersonal outcomes. Specifically, more negative impressions and affect will be directed toward high-status individuals who make external attributions than toward their lower status counterparts. Three studies were conducted, one using a role-play methodology, one using an experimentally created hierarchy, and one using vignettes. The results supported our hypotheses: external attributions can be highly disserving for people in high-status positions.     

Visual representation of malleable and rigid objects that deform as they rotate

Most studies and theories of object recognition have addressed the perception of rigid objects. Yet, physical objects may also move in a nonrigid manner. A series of priming studies examined the conditions under which observers can recognize novel views of objects moving nonrigidly. Observers were primed with 2 views of a rotating object that were linked by apparent motion or presented statically. The apparent malleability of the rotating prime object varied such that the object appeared to be either malleable or rigid. Novel deformed views of malleable objects were primed when falling within the object's motion path. Priming patterns were significantly more restricted for deformed views of rigid objects. These results suggest that moving malleable objects may be represented as continuous events, whereas rigid objects may not. That is, object representations may be "dynamically remapped" during the analysis of the object's motion.