Haptic underestimation of angular extent

To what extent can individuals accurately estimate the angle between two surfaces through touch alone, and how does tactile judgment compare to visual judgment? Subjects' ability to estimate angle size for a variety of haptic and visual stimuli was examined in a series of nine experiments. Triangular wooden blocks and raised contour outlines comprising different angles and radii of curvature at the apex were used in experiments 1-4 and it was found that subjects consistently underestimated angular extent relative to visual baselines and that the degree of underestimation was inversely related to the actual size of the angle. Angle estimates also increased with increasing radius of curvature when actual angle size was held constant. In contrast, experiments 5-8 showed that subjects did not underestimate angular extent when asked to perform a haptic-visual match to a computerized visual image; this outcome suggests that visual input may 'recalibrate' the haptic system's internal metric for estimating angle. The basis of this cross-modal interaction was investigated in experiment 9 by varying the nature and extent of visual cues available in haptic estimation tasks. The addition of visual-spatial cues did not significantly reduce the magnitude of haptic underestimation. The experiments as a whole indicate that haptic underestimations of angle occur in a number of different stimulus contexts, but leave open the question of exactly what type of visual information may serve to recalibrate touch in this regard.     

Cross-modality matching functions generated by magnitude estimation

It is possible to generate cross-modality matching functions by having subjects make magnitude estimates of sets of stimuli appropriate to different modalities. The sets are interspersed among each other in the same test session and judged on a common absolute scale of sensory magnitude. An appropriate statistical device locates stimulus levels that appear, on the average, to match. The method is fast, efficient, circumvents the need for continuous stimulus adjustment, and holds promise for the study of the individual as well as the average psychophysical function. To illustrate its potential uses, advantages, and limitations, we used the method to generate cross-modality matching functions relating loudness and brightness. Compared to the scales of loudness and brightness generated by the magnitude estimations of the same stimuli, the matching functions (1) conform better to power functions, (2) may show less variation in slope (exponent), and (3) show far less variation in absolute magnitude (position).     

Haptic perception of linear extent

The perception of linear extent in haptic touch appears to be anisotropic, in that haptically perceived extents can depend on the spatial orientation and location of the object and, thus, on the direction of exploratory motion. Experiments 1 and 2 quantified how the haptic perception of linear extent depended on the type of motion (radial or tangential to the body) when subjects explored different stimulus objects (raised lines or solid blocks) varying in length and in relative spatial location. Relatively narrow, shallow, raised lines were judged to be longer, by magnitude estimation, than solid blocks. Consistent with earlier reports, stimuli explored with radial arm motions were judged to be longer than identical stimuli explored with tangential motions; this difference did not depend consistently on the lateral position of the stimulus object, the direction of movement (toward or away from the body), or the distance of the hand from the body but did depend slightly on the angular position of the shoulder. Experiment 3 showed that the radial-tangential effect could be explained by temporal differences in exploratory movements, implying that the apparent anisotropy is not intrinsic to the structure of haptic space.     

Toward neuroanatomical models of analogy: a positron emission tomography study of analogical mapping

Several brain regions associated with analogical mapping were identified using (15)O-positron emission tomography with 12 normal, high intelligence adults. Each trial presented during scanning consisted of a source picture of colored geometric shapes, a brief delay, and a target picture of colored geometric shapes. Analogous pictures did not share similar geometric shapes but did share the same system of abstract visuospatial relations. Participants judged whether each source-target pairing was analogous (analogy condition) or identical (literal condition). The results of the analogy-literal comparison showed activation in the dorsomedial frontal cortex and in the left hemisphere; the inferior, middle, and medial frontal cortices; the parietal cortex; and the superior occipital cortex. Based on these results as well as evidence from relevant cognitive neuroscience studies of reasoning and of executive working memory, we hypothesize that analogical mapping is mediated by the left prefrontal and inferior parietal cortices.     

Predictors of physical aggression in children with attention-deficit/hyperactivity disorder

The present investigation examined factors that predict physical aggression in children with attention-deficit/hyperactivity disorder (ADHD). Stepwise, multiple regression-analyses were used to examine predictors of children's physical aggression as rated by parents at a 1-year follow-up point and by teachers at both 1- and 2-year follow-up points. Early parent and teacher ratings of verbal aggression (ie, cursing, teasing, and threatening) accounted for the greatest proportion of the variance in physical aggression ratings obtained at follow-up. None of the other predictor variables, including early ratings of physical aggression and ADHD behaviors, contributed significant additional variance beyond that accounted for by early verbal aggression ratings. Temporal and cross-informant analyses revealed that the relationship between verbal aggression and later physical aggression was situation-specific for teacher ratings but not parent ratings. Although physical aggression may emerge early in development, these data suggest that verbal aggression represents a stable, temperamental characteristic that may be of greater value than early physical aggression for predicting later physically aggressive acts.     

Brighter noise: Sensory enhancement of perceived loudness by concurrent visual stimulation

Two experiments investigated the effect of concurrently presented light on the perceived loudness of a low-level burst of white noise. The results suggest two points. First, white noise presented with light tends to be rated as louder than noise presented alone. Second, the enhancement in loudness judgments is resistant to two experimental manipulations: varying the probability that light accompanies sound and shifting from a rating method to a forced choice comparison. Both manipulations were previously shown to eliminate a complementary noise-induced enhancement in ratings of brightness. Whereas noise-induced enhancement of brightness seems to reflect a late-stage decisional process, such as a response bias, the present results suggest that light-induced enhancement of loudness may reflect an early-stage sensory interaction.     

Recalibrating the auditory system: a speed-accuracy analysis of intensity perception

Recalibration in loudness perception refers to an adaptation-like change in relative responsiveness to auditory signals of different sound frequencies. Listening to relatively weak tones at one frequency and stronger tones at another makes the latter appear softer. The authors showed recalibration not only in magnitude estimates of loudness but also in simple response times (RTs) and choice RTs. RTs depend on sound intensity and may serve as surrogates for loudness. Most important, the speeded classification paradigm also provided measures of errors. RTs and errors can serve jointly to distinguish changes in sensitivity from changes in response criterion. The changes in choice RT under different recalibrating conditions were not accompanied by changes in error rates predicted by the speed-accuracy tade-off. These results lend support to the hypothesis that loudness recalibration does not result from shifting decisional criteria but instead reflects a change in the underlying representation of auditory intensity.