James A. Thomson

Is continuous visual monitoring necessary in visually guided locomotion

Subjects were asked to walk to targets that were up to 21 m away, either with vision excluded during walking or under normal visual control. Over the entire range, subjects were accurate whether or not vision was available as long as no more than approximately 8 sec elapsed between closing the eyes and reaching the target. If more than 8 sec elapsed, (a) this had no influence on distances up to 5 m, but (b) distances between 6-21 m were severely impaired. The results are interpreted to mean that two mechanisms are involved in guidance. Up to 5 m, motor programs of relatively long duration can be formulated and used to control activity. Over greater distances, subjects internalized information about the environment in a more general form, independently of any particular set of motor instructions, and used this to control activity and formulate new motor programs. Experiments in support of this interpretation are presented.

Influence of virtual reality training on the roadside crossing judgments of child pedestrians.

The roadside crossing judgments of children aged 7, 9, and 11 years were assessed relative to controls before and after training with a computer-simulated traffic environment. Trained children crossed more quickly, and their estimated crossing times became better aligned with actual crossing times. They crossed more promptly, missed fewer safe opportunities to cross, accepted smaller traffic gaps without increasing the number of risky crossings, and showed better conceptual understanding of the factors to be considered when making crossing judgments. All age groups improved to the same extent, and there was no deterioration when children were retested 8 months later. The results are discussed in relation to theoretical arguments concerning the extent to which childrens pedestrian judgments are amenable to training.

How do we use visual information to control locomotion

We are accustomed to thinking that we need to use vision all the time to guide us as we walk about in the world. However, recent experiments are beginning to show that vision might be used less than we normally imagine.

Automatic spatial updating during locomotion without vision

People can update their spatial relationships relative to the environment while walking without vision. The hypothesis that such updating is automatic was tested in a locomotor task in which the subjects were asked to refrain from updating their positions. Subjects walked without vision to one of four previously seen targets via a second location. In one condition—the updating condition—the subjects were asked to walk to the real position of the target relative to the second location; in another—the ignoring condition—they were asked to imagine that they had not moved from the starting point and to walk from the second location as if walking to the target from the initial location. When the subjects were asked to start walking to the target as soon as it was named by the experimenter, they performed better in the updating condition than in the ignoring condition. When the subjects were allowed more time to respond, the difference in performance between these two conditions disappeared. The results suggest that the subjects automatically updated their positions as they moved, but that, given enough time, they could override this updating retrospectively using more deliberate cognitive processing.

The effects of adult guidance and peer discussion on the development of children's representations: evidence from the training of pedestrian skills

It was hypothesized that practical training is effective in improving childrens pedestrian skills because adult scaffolding and peer discussion during training specifically promote E3 level representation (linguistically-encoded, experientially-grounded, generalizable knowledge), as defined by Karmiloff-Smiths (1992) representational redescription (RR) model. Two studies were conducted to examine in detail the impact of this social input in the context of simulation-based training in roadside search skills. A group of 5-8-year-olds were pre-tested on ability to detect relevant road-crossing features. They then participated in four training sessions designed to promote attunement to these, under peer discussion versus adult guidance conditions (Study 1), and adult-child versus adult-group conditions (Study 2). Performance at post-test was compared with that of controls who underwent no training. Study 1 found that children in the adult guidance condition improved significantly more than those in the peer discussion or control conditions, and this improvement was directly attributable to appropriation of E3 level representations from adult dialogue. Study 2 found that progress was greater still when adult scaffolding was supplemented by peer discussion, with E3 level representation attributable to the childrens exploration of conflicting ideas. The implications of these findings for the RR model and for practical road safety education are discussed.

On-Line Updating of Spatial Information During Locomotion Without Vision

Two experiments are reported in which the control of locomotion without vision was investigated. In Experiment 1, subjects (N = 10) made similar, although less functional, locomotor adjustments when walking without vision to a target than they did when walking with vision. That result suggests that while walking without vision, the subjects updated their positions on-line with respect to a representation of the target rather than operating from a preformulated action plan. In Experiment 2, there was a significant weakening and loss of functionality of the locomotor adjustments when subjects (N = 10) had to walk without vision the correct distance to the target but in a direction opposite to its true location, as compared with when they walked without vision directly to the target. That finding suggests that the subjects were nonvisually updating their positions not with respect to an abstract representation of the targets distance but with respect to a representation of its relative location within the task environment.

Evidence that changes in social cognitions predict changes in self-reported driver behavior: causal analyses of two-wave panel data

Previous research on the theory of planned behavior (TPB) is characterized by cross-sectional tests of the models proposed causal relationships. In the absence of effective experimental techniques for changing the TPBs cognitive antecedents, the present research aimed to provide a stronger non-experimental test of the model, using causal analyses of two-wave panel data. Two studies of driver behavior were conducted in which naturally occurring within-participant changes in TPB constructs were measured over time, and used to predict corresponding within-participant changes in both intentions and behavior. A two-wave panel design was used in both studies. Study 1 had a one-month gap between baseline and follow-up. At both waves, a convenience sample comprising predominantly university students (N=135) completed questionnaire measures of all TPB cognitions and behavior (compliance with speed limits in urban areas). Cross-lagged multiple regressions and bootstrapping procedures for testing multiple mediators supported all of the relationships proposed by the TPB. These findings were extended in study 2 using a large, non-student sample of speed limit offenders (N=1149), a six-month gap between baseline and follow-up, and a larger number of cognitive antecedents. Participants completed postal questionnaires at both waves to measure all cognitions proposed by the two-component TPB, along with moral norm, anticipated regret, self-identity and speeding on urban roads, country roads, and fast dual carriageways or motorways. Changes in instrumental and affective attitude, descriptive norm, self-efficacy, moral norm, anticipated regret and self-identity predicted changes in intention to speed. Changes in intention and self-efficacy predicted behavior-change. Injunctive norm and perceived controllability did not predict intention or behavior-change. Additionally, direct (unhypothesized) relationships with behavior were found for affective attitude, descriptive norm and anticipated regret. The implications of the findings for theory and the development of effective behavior-change interventions are discussed.

Intermittent Versus Continuous Visual Control: A Reply to Elliott

Recently, Elliott (1986) has reported data that he claims are inconsistent with my hypothesis that a short-term motor memory system exists for guiding locomotion and other actions in space (Thomson, 1983). In fact, methodological flaws in Elliotts design make such conclusions unjustified and inappropriate. Moreover, insofar as comparisons can be made at all, the results are completely consistent with my own data.

Cognitive and Motor Representations of Space and Their Use in Human Visually-Guided Locomotion

The ability of animals to move around their environments, encountering or avoiding objects; knowing where to seek them out; or finding their way to a distant home that is out of sight, all depend on a complex combination of perceptual and motor skills that has long preoccupied students of behaviour. On the one hand, a vast animal literature has developed to investigate how animals learn to operate in large scale environments, whether using classical psychological techniques in the laboratory or the field study methods of ethology in natural environments. These problems have also increasingly attracted students of human behaviour, particularly in a developmental context, and such research is well-represented in the present volume. All such studies, however, have in common a concern with the development of long-term representations of space, internalised through prolonged interaction with the environment. Moreover, such representations are almost always truly cognitive, in that the environment to be represented is seldom seen all at one time, but is constructed on the basis of viewpoints sampled at different times. Here we present evidence of a different type of spatial representation, appearing at the one time more sensory in nature, yet bearing many of the features of cognitive representations. Our aim here will be to describe such representations and discuss their possible role in spatial orientation.

Issues in safety education interventions

The Lifeskills team and their sponsors are to be congratulated for the evaluation reported in this issue