An Affordance-Based Approach to Visually Guided Overtaking

When an automobile driver overtakes a lead vehicle while avoiding oncoming traffic, does he or she do so with reference to the limits of his or her car? We investigated overtaking from the perspective of the theory of affordances. We define the overtake-ability affordance as a ratio of the minimum satisfying velocity required for safe overtaking (MSV) to the maximum velocity of the driver's car (V_max). Two groups of participants performed overtaking maneuvers, if deemed possible, by driving either a slow (V_max = 25 m/s) or a fast (V_max = 32.5 m/s) virtual car in overtaking situations constrained by 14 values of MSV. For any given MSV condition, participants in the fast car group were more likely to attempt an overtaking maneuver. However, when MSV was expressed in intrinsic units as a ratio of V_max for both groups, the frequency of overtaking was not significantly different across groups. Furthermore, overtaking frequency dropped to near 0% for both groups when MSV exceeded V_max. In accordance with the affordance-based framework (Fajen, 2007), our results suggest that participants select their overtaking maneuvers by perceiving an overtake-ability affordance.     

A Rorschach stability study in a nonpatient adult sample

The objective of this study was to provide new primary data on Rorschach Comprehensive System stability levels. To achieve this, we tested 75 French nonpatient adults twice on the Rorschach with a 3-month interval between the tests. Interrater reliability was in the excellent range for most of the variables studied. The overall stability level in a selected set of previously studied variables was below expectations (median r = .53). Personality, cognitive or self/relational variables yielded higher test-retest correlations than emotional and coping variables. Moderators of stability could be identified: (a) overall level of Task Engagement (TE) in F, m, FM + m, a, FC, Sum C', Sum V, Sum Shd, Fr + rF, INC + FAB, COP, es, Adj es, EGO, and Blends; (b) variations in TE in F, FM, and p; (c) state distress in Zd, m, FM + m, a, C, CF + C, WSumC, FD, and es; (d) variables derived from the number of responses impacted stability in P, Zf, m, FC, CF + C, Sum C', Sum V, MOR, EA, es, and Blends. These results provide further support for the reliability of several measures. Examiner effects as an influence on productivity and TE were identified as an important area for future research.     

Muscular proprioception contributes to the control of interceptive actions

The authors proposed a model of the control of interceptive action over a ground plane (Chardenon, Montagne, Laurent, & Bootsma, 2004). This model is based on the cancellation of the rate of change of the angle between the current position of the target and the direction of displacement (i.e., the bearing angle). While several sources of visual information specify this angle, the contribution of proprioceptive information has not been directly tested. In this study, the authors used a virtual reality setup to study the role of proprioception when intercepting a moving target. In a series of experiments, the authors manipulated proprioceptive information by using the tendon vibration paradigm. The results revealed that proprioception is crucial not only to locate a moving target with respect to the body but also, and more importantly, to produce online displacement velocity changes to intercept a moving target. These findings emphasize the importance of proprioception in the control of interceptive action and illustrate the relevance of our model to account for the regulations produced by the participants.     

Gaze avoidance in social phobia: Objective measure and correlates

Gaze aversion could be a central component of the physiopathology of social phobia. The emotions of the people interacting with a person with social phobia seem to model this gaze aversion. Our research consists of testing gaze aversion in subjects with social phobia compared to control subjects in different emotional faces of men and women using an eye tracker. Twenty-six subjects with DSM-IV social phobia were recruited. Twenty-four healthy subjects aged and sex-matched constituted the control group. We looked at the number of fixations and the dwell time in the eyes area on the pictures. The main findings of this research are: confirming a significantly lower amount of fixations and dwell time in patients with social phobia as a general mean and for the 6 basic emotions independently from gender; observing a significant correlation between the severity of the phobia and the degree of gaze avoidance. However, no difference in gaze avoidance according to subject/picture gender matching was observed. These findings confirm and extend some previous results, and suggest that eye avoidance is a robust marker of persons with social phobia, which could be used as a behavioral phenotype for brain imagery studies on this disorder.     

The Role of Concurrent Feedback in Learning to Walk Through Sliding Doors

Concurrent feedback is defined as information about performance given to participants during the execution of an action. This article investigates whether concurrent feedback is beneficial or detrimental to the learning of an ecologically relevant task. Eighteen participants were asked to walk through a virtual corridor and they practiced over 1110 trials to adjust their walking speed so as to pass through sliding doors that opened and closed at a frequency of 1 Hz. Concurrent feedback informed them about the possible need to accelerate or decelerate. Performance of participants who received concurrent feedback on 66% of the practice trials (on average) did not differ significantly from performance of participants who did not receive concurrent feedback. Furthermore, participants of both of these groups significantly outperformed participants who received concurrent feedback on all practice trials. These results are discussed in relation to the perceptual-motor mechanisms that underlie the control of the action. Also discussed are implications for future research, including the use of self-controlled feedback and the use of multisensory training programs.     

Resource depletion does not influence prospective memory in college students

This paper reports an experiment designed to investigate the potential influence of prior acts of self-control on subsequent prospective memory performance. College undergraduates (n = 146) performed either a cognitively depleting initial task (e.g., mostly incongruent Stroop task) or a less resource-consuming version of that task (e.g., all congruent Stroop task). Subsequently, participants completed a prospective memory task that required attentionally demanding monitoring processes. The results demonstrated that prior acts of self-control do not impair the ability to execute a future intention in college-aged adults. We conceptually replicated these results in three additional depletion and prospective memory experiments. This research extends a growing number of studies demonstrating the boundary conditions of the resource depletion effect in cognitive tasks.     

Age-Related Changes in Grip Force and Dynamics of Hand Movement

The authors investigated whether older adults (n = 16; mean age = 65 years) increased grip force to compensate for load force fluctuations during up and down movements more than young adults did (n = 16; mean age = 24 years) and whether older and young adults exhibited similar adaptation of grip force to alterations in friction associated with changes in object surface texture. As previously reported, older adults used a higher level of grip force than young adults during static holding. Increased grip force was observed in the older group during movement. The increase was appropriate to the lower coefficient of friction estimated for the older group. In both groups, grip force was greater with a smooth than with a rough surface (the latter having the higher coefficient of friction) during static holding and during movement. Moreover, grip force modulation was equally well synchronized with load force fluctuation during movement in the two groups. The authors concluded that changes in organization of grip force with age are well adapted to change in hand-object interface properties. Elevated grip force in older adults does not necessarily signify a fundamental change in synchronizing grip force modulation with load force fluctuation.     

Bifactor Modeling and the Estimation of Model-Based Reliability in the WAIS-IV

Previous confirmatory factor analytic research that has examined the factor structure of the Wechsler Adult Intelligence Scale–Fourth Edition (WAIS-IV) has endorsed either higher order models or oblique factor models that tend to amalgamate both general factor and index factor sources of systematic variance. An alternative model that has not yet been examined for the WAIS-IV is the bifactor model. Bifactor models allow all subtests to load onto both the general factor and their respective index factor directly. Bifactor models are also particularly amenable to the estimation of model-based reliabilities for both global composite scores (ω _h ) and subscale/index scores (ω _s ). Based on the WAIS-IV normative sample correlation matrices, a bifactor model that did not include any index factor cross loadings or correlated residuals was found to be better fitting than the conventional higher order and oblique factor models. Although the ω _h estimate associated with the full scale intelligence quotient (FSIQ) scores was respectably high (.86), the ω _s estimates associated with the WAIS-IV index scores were very low (.13 to .47). The results are interpreted in the context of the benefits of a bifactor modeling approach. Additionally, in light of the very low levels of unique internal consistency reliabilities associated with the index scores, it is contended that clinical index score interpretations are probably not justifiable.     

Prospective remembering: Perceptually driven or conceptually driven processes?

Converging experimental operations and several prospective memory tasks were used across three experiments to determine the extent to which prospective remembering is supported by datadriven versus conceptually driven processes. In all experiments, subjects were asked to perform an action when a target item later occurred. When the semantic context changed from encoding to test, prospective memory significantly declined (Experiment 1). When the target event (the item, which in its subsequent appearance in the experiment was the signal to perform the action) was presented as a word (relative to picture presentation, Experiment 2) or was encoded nonsemantically (relative to semantic encoding, Experiment 3), there was a decline in prospective memory performance. Dividing attention during prospective memory retrieval substantially reduced prospective memory performance (Experiment 3). The results of this research indicated that prospective memory is largely conceptually driven, and it behaves more similarly to direct rather than indirect conceptual tests. We suggest that prospective remembering of the type studied here is mediated by a reflexive episodic associative memory system as proposed by Moscovitch (1994).