Do you see what I see? Co-actor posture modulates visual processing in joint tasks

ABSTRACT

Interacting with other people is a ubiquitous part of daily life. A complex set of processes enable our successful interactions with others. The present research was conducted to investigate how the processing of visual stimuli may be affected by the presence and the hand posture of a co-actor. Experiments conducted with participants acting alone have revealed that the distance from the stimulus to the hand of a participant can alter visual processing. In the main experiment of the present paper, we asked whether this posture-related source of visual bias persists when participants share the task with another person. The effect of personal and co-actor hand-proximity on visual processing was assessed through object-specific benefits to visual recognition in a task performed by two co-actors. Pairs of participants completed a joint visual recognition task and, across different blocks of trials, the position of their own hands and of their partner's hands varied relative to the stimuli. In contrast to control studies conducted with participants acting alone, an object-specific recognition benefit was found across all hand location conditions. These data suggest that visual processing is, in some cases, sensitive to the posture of a co-actor.     

A Comparison of Multilevel Imputation Schemes for Random Coefficient Models: Fully Conditional Specification and Joint Model Imputation with Random Covariance Matrices

Abstract

Literature addressing missing data handling for random coefficient models is particularly scant, and the few studies to date have focused on the fully conditional specification framework and “reverse random coefficient” imputation. Although it has not received much attention in the literature, a joint modeling strategy that uses random within-cluster covariance matrices to preserve cluster-specific associations is a promising alternative for random coefficient analyses. This study is apparently the first to directly compare these procedures. Analytic results suggest that both imputation procedures can introduce bias-inducing incompatibilities with a random coefficient analysis model. Problems with fully conditional specification result from an incorrect distributional assumption, whereas joint imputation uses an underparameterized model that assumes uncorrelated intercepts and slopes. Monte Carlo simulations suggest that biases from these issues are tolerable if the missing data rate is 10% or lower and the sample is composed of at least 30 clusters with 15 observations per group. Furthermore, fully conditional specification tends to be superior with intraclass correlations that are typical of crosssectional data (e.g., ICC?=?.10), whereas the joint model is preferable with high values typical of longitudinal designs (e.g., ICC?=?.50).     

Reproducing the End Location of a Positioning Movement

Two experiments were conducted in an attempt to determine the conditions under which shifts in the starting position of a linear positioning response influenced the reproduction of the end location of movements of various lengths. In Experiment 1, response bias (i.e., shift in constant error) was affected by the direction of the shift in starting position between presentation and recall. For short (20 cm) and medium (50 cm) length movements, this relationship was evident regardless of hand used (left or right), direction of the movement (left to right or right to left), and length of the retention interval (5 or 45 s). However, no relation between response bias and the direction of starting position shifts was apparent for long (80 cm) movements. The results of Experiment 2 in which more movement lengths were used revealed a response bias that corresponded to shifts in starting position primarily during the first few reproductions of the two shortest movements (20 and 30 cm). However, no systematic bias was evident for any length movement after three reproduction attempts. Possible strategies used by subjects to reproduce the end location of movements of various lengths were discussed.     

Influence of Practice Schedule on Testing Schema Theory Predictions in Adults

Since the publication of Schmidt’s (1975) schema theory of motor learning, numerous studies have assessed the variability of practice hypothesis. Of these, only research using children as subjects has provided consistent results. Findings from adult studies have been equivocal. Two experiments were conducted to assess the possibility that the schedule of variable practice during acquisition may be a clue to this equivocality, since only experiments (using adults as subjects) that have provided random variability of practice conditions have consistently supported the tenets of schema theory. Using a two movement rapid timing task, subjects learned to control their actions under one (constant) or four (variable) parameters, with variable practice conducted under either a blocked or a randomized schedule. Results for variable error and absolute constant error showed that random-variable practice provided strong support for the schema theory prediction, whereas blocked-variable practice provided only relatively weak support. Two contrasting implications of these results are discussed with respect to support versus non-support for Schmidt’s schema theory.     

Moral Beliefs,Isolation from Peers,and Abstention from Delinquency

Criminological research has established that the vast majority of young people engage in some level of delinquency and drug use during the period of adolescence. Thus young people who completely refrain from delinquency and drug use are atypical and, as such, are deserving of scientific scrutiny. Perhaps because they have been impressed by the statistical abnormality of delinquency abstention, some researchers have explained this behavior in terms of the characterological abnormality of abstainers, arguing that abstention may be less the result of positive characteristics (such as strong moral beliefs) than the result of pathological traits that serve to isolate abstainers from their peers. In this study, data from a large survey of adolescents are used to help assess the respective roles of moral beliefs and peer isolation in delinquency abstention. The findings challenge certain previous interpretations of delinquency abstention and shed additional light on the forces that help to sustain adolescent conformity. The findings also raise intriguing questions about the stigma attached to delinquency abstainers.     

Protecting Self-Image: The Rationalization of Cheating in an International Billiard League

ABSTRACT

The American Poolplayers Association, founded in 1979, is an international billiard league established in the United States, Canada, and Japan, with more than 250,000 members. The most difficult problem facing the American Poolplayers Association (APA)’s league operators is the deliberate cheating by the competing players. Players cheat to lower their skill level, allowing them to win more easily in important billiard matches such as the APA international championships. Qualitative interviews revealed that when asked about their cheating behavior, the players used all five “techniques of neutralization to rationalize their actions attempting to protect their self-image and to help insulate them from external judgments.     

Contextual Interference in Motor Learning: Dissociated Effects Due to the Nature of Task Variations

The contextual interference effect in motor learning refers to the interference that results from practising a task within the concept of other tasks in a practice session. Several studies have shown that practice under conditions of high contextual interference (i.e. with a random practice order) degrades performance during acquisition trials, compared to low contextual interference conditions (i.e. with a blocked order, where practice is completed on one task before practice on another task is undertaken). In contrast to acquisition performance, random practice usually leads to more effective learning than blocked practice, as measured by retention and transfer tests. One of the hypotheses regarding the effect suggests that a random practice schedule induces more extensive planning operations during practice than a blocked practice condition. If so, then differences between these two conditions should emerge to the degree that the set of tasks requires complete reconstruction of these planning operations on each trial. To address this issue, we compared four groups of subjects: a blocked and random group that practised three timing tasks that shared a common characteristic (same relative timing), and a blocked and random group that practised three tasks that each had different relative timing structures. Subjects practised these tasks on each of two days, with a retention test and two transfer tests that required either a relative timing structure that had been practised previously or had not previously been practised. No random/ blocked differences occurred regardless of the relative timing of the patterns during acquisition or retention. However, for both transfer tests, random practice enhanced learning only for the group that had practised with tasks that each had different relative timing during acquisition. Implications of these results for an explanation of contextual interference are discussed.     

Diego Duarte <Emphasis Type="SmallCaps">ii</Emphasis> (1612–1691): a <Emphasis Type="Italic">converso</Emphasis>’s experience in seventeenth-century Antwerp

From the early sixteenth century onward, many conversos or New Christians left Spain and Portugal and went to Antwerp. One member of the converso community in Antwerp was Diego Duarte ii (1612–1691). Diego Duarte ran a thriving jewel business and had a large commercial network. He was also a highly cultured man, who forged many friendships through his love for music and paintings. Antwerp was, however, still off-limits for Jews. This article seeks to explore Diego’s professional, religious and, in particular, his artistic background seen against the place and time in which he lived.