Multimodal Perception of Reachability Expressed Through Locomotion

We investigated the information that supports perception of whether an object is within reach using a locomotor task. Participants adjusted their own position relative to a fixed target by stepping or by propelling a wheelchair until they judged it to be within reach. The to-be-reached object was presented in virtual reality. The display of the target was driven in real time as a function of the observer's movement, thus depicting a stationary virtual object at a definite distance only through the relation across optical and nonoptical patterns of stimulation. We asked participants to judge the distance they could reach with their unaided hand or when holding a rod that extended their effective reach. They could see neither their body nor the rod thereby limiting available visual information about “reachability.” As expected, our results showed that despite the limited information that was available, participants' locomotor adjustments were influenced by (a) their simulated distance from the target, (b) their arm length, and (c) the presence or absence of the rod. The type of motion (stepping or wheelchair) had little influence. However, judgment accuracy was influenced by participants' initial simulated distance from the target. We compare the performance obtained in our locomotor judgment task with previous studies that have used different methods for measuring perceived reaching-ability. We discuss perceptual information that could have supported performance within the framework of the global array.     

Fitting in but getting fat: identity threat and dietary choices among U.S. immigrant groups

In two experiments, we tested the hypothesis that pressure felt by U.S. immigrant groups to prove they belong in America causes them to consume more prototypically American, and consequently less healthy, foods. Asian Americans were three times more likely to report a prototypically American food as their favorite after being asked whether they spoke English than when they had not been asked; in contrast, questioning the English abilities of White Americans had no effect on their reports (Experiment 1). Also, Asian Americans ordered and ate dishes that were more American and contained an average of 182 additional calories and 12 extra grams of fat when their American identity was directly challenged than when their American identity was not challenged (Experiment 2). Identity-based psychological processes may help explain why the diets of U.S. immigrant groups tend to decline in nutritional value with longer residence in the United States and over generations.     

Letting people off the hook: when do good deeds excuse transgressions?

Three studies examined when and why an actor's prior good deeds make observers more willing to excuse--or license--his or her subsequent, morally dubious behavior. In a pilot study, actors' good deeds made participants more forgiving of the actors' subsequent transgressions. In Study 1, participants only licensed blatant transgressions that were in a different domain than actors' good deeds; blatant transgressions in the same domain appeared hypocritical and suppressed licensing (e.g., fighting adolescent drug use excused sexual harassment, but fighting sexual harassment did not). Study 2 replicated these effects and showed that good deeds made observers license ambiguous transgressions (e.g., behavior that might or might not represent sexual harassment) regardless of whether the good deeds and the transgression were in the same or in a different domain--but only same-domain good deeds did so by changing participants' construal of the transgressions. Discussion integrates two models of why licensing occurs.     

The multiple dual-pair method

A model for the multiple dual-pair method, a generalization of the traditional dual-pair (4IAX) paradigm, is given. This model is expressed in terms of normal and beta distributions. This generalization allows for the simultaneous estimation of the perceptual distances among three or more stimuli. This model has applications in cases in which multiple two-sample comparisons would be too time consuming and labor intensive. The theory discussed shows how unequal variances can be estimated on the basis of results from that method. Two numerical examples that illustrate the ability of the beta distribution-based model to retrieve the appropriate parameters are given. It is also shown how the traditional dual-pair model is a special case of the multiple dual-pair model.     

Selective attention in major depression: clinical retardation and cognitive inhibition]

Relationships between clinical retardation (measured by the Hamilton Depression Inventory) and selective attention (measured with a computerized version of the Stroop word colour test) were studied in a population of 21 depressed patients. Stroop interference was higher in depressed patients than in normals. Desynchronized presentations of the distractor and the target and intervals between responses and succeeding stimuli permitted depressed subjects to respectively apply and lift inhibition of the distractor so that their interference was reduced to control levels. Finally, successive inhibition scores were correlated with the retardation score in depressed subjects. The results are consistent with the hypothesis of a retardation in the application and the lifting of cognitive inhibition in depression.     

A Thurstonian model for the dual pair (4IAX) discrimination method

The Institute for Perception, Richmond, Virginia In the dual pair method, the subject is presented with two stimuli in two pairs: One pair is composed of two samples of the same stimulus; the other pair is composed of two samples of different stimuli, one being the same as that in the identical pair. The task of the judge is to select the most different pair. The psychometric function for the dual pair method is derived and expressed in terms of a singly noncentral beta distribution. A table is provided that connects a measure of the degree of difference, d , to the probability of a correct response. This table assumes an unbiased observer and differencing decision rule. A table is provided to give an estimate of the variance of d¢, the experimental estimate of d. The power of the dual pair method is also investigated, and a formula to determine the sample size required to meet Type I and Type II error specifications is given. The dual pair method appears to be slightly less powerful than the duotrio and the triangular methods. Experimental investigation is needed to explore the dual pair in applied research work.     

An analysis of reading skill development using E-Z Reader

Previously reported simulations using the E-Z Reader model of eye-movement control suggest that the patterns of eye movements observed with children versus adult readers reflect differences in lexical processing proficiency. However, these simulations fail to specify precisely what aspect(s) of lexical processing (e.g., orthographic processing) account for the concurrent changes in eye movements and reading skill. To examine this issue, the E-Z Reader model was first used to simulate the aggregate eye-movement data from 15 adults and 75 children to replicate the finding that gross differences in reading skill can be accounted for by differences in lexical processing proficiency. The model was then used to simulate the eye-movement data of individual children so that the best-fitting lexical processing parameters could be correlated to measures of orthographic knowledge, phonological processing skill, sentence comprehension, and general intelligence. These analyses suggest that orthographic knowledge accounts for variance in the eye-movement measures that is observed with between-individual differences in reading skill. The theoretical implications of this conclusion will be discussed in relation to computational models of reading and our understanding of reading skill development.     

Dynamics of human postural transitions

In the present study, the authors examined transitions between postural coordination modes involved in human stance. The analysis was motivated by dynamical theories of pattern formation, in which coordination modes and transitions between modes are emergent, self-organized properties of the dynamics of animal-environment systems. In 2 experiments, standing participants tracked a moving target with the head. Results are consistent with the hypothesis that changes in body coordination follow typical nonequilibrium phase transitions, exhibiting multistability, bifurcation, critical fluctuations, hysteresis, and critical slowing down. The findings suggest that posture may be organized in terms of dynamical principles and favor the existence of general and common principles governing pattern formation and flexibility in complex systems.