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Biomedical subjects

A Costall

Publications and source records attributed to A Costall.

10 recordsLinked to original sources
PubMed2002

Drifting towards a diffuse control model of exploratory motor learning: A comparison of global and within-trial performance measures.

Accurate measurement is crucial for understanding the processes that underlie exploratory patterns in motor learning. Accordingly, measures of learning should be sensitive to the changes that take place during skill acquisition. Most studies, however, use trial-based global measures that assess performance but do not actually measure gradual changes taking place within trials. The present study attempted to remedy this shortcoming by analysing a visual adaptation task, and comparing traditional global measures of learning with new, within-trial measures. Movement time was the only global measure sensitive to changes in the movement trajectory during learning. Three new measures were expected to reveal changes to the movement trajectory that are associated with learning: (i) the length of runs, (ii) change of trajectory angle in relation to the target, and (iii) drift (change in distance from the target). All three measures were sensitive to learning and indicated a gradual straightening of the movement trajectories over trials. Furthermore, three different methods to partition trajectories into segments were examined. The new within-trial measures, irrespective of partitioning method, prove promising for the development of a diffuse control model of exploratory learning.

Exploratory Behavior↗
PubMed2001

Taking a closer look at functional play in children with autism.

Research evidence indicates that children with autism may experience problems with functional play, in addition to their well-documented deficits in symbolic play. However, as a result of the tendency of previous studies to group all functional play into a single category, the precise nature and extent of this deficit remains unclear. The present study undertook a more refined analysis of such play, subtyping the functional acts into various categories, in terms of the developmental progression suggested by research with typical infants. The functional play of children with autism was compared to that of developmentally matched children with Down syndrome and typical infants. Although there were no group differences in overall measures of the proportion of total play time spent in functional play and in the number of functional acts performed, a closer analysis of the composition of this play did reveal striking, qualitative differences. The functional play of the autism group was less elaborated, less varied, and less integrated than that of the controls. The implications of these findings are explored in relation to current theoretical models of autism and in relation to the role of other people in mediating the appropriate use of objects.

Activities of Daily Living↗
PubMed2001

A kinematic analysis of hand selection in a reaching task.

A group of left- and right-handers was tested on a task requiring them to reach out and pick up an object with either the left or the right hand. We varied the eccentricity of the target object (a small glass) and the required accuracy level, by filling the glass with liquid. We recorded (a) frequency of left or right hand use, (b) hand preference using a handedness questionnaire, and (c) the trajectories of the reaches using a movement registration system. It was found that the stronger the hand preference, the further in contralateral space the shift occurred between left and right hand use. Not only did the transition point corresponding to the shift between the two hands correlate with the point where their deceleration times were equal, but these locations closely coincided. These findings suggest that people are highly skilled perceivers of their own action capabilities, and that they are able to select the action mode that is most suited to perform a given task. We argue that laterality should be understood in terms of asymmetries in action modes.

Journal Article↗
PubMed1999

Dire straits: the divisive legacy of the 1898 Cambridge anthropological expedition.

Bartlett's claim that the Cambridge anthropological expedition of 1898 to the Torres Strait "put a social and ethnological stamp upon Cambridge psychology" does not bear close examination. Rivers pursued his interests in both anthropology and psychology but came to regard them as largely independent pursuits. Myers, through the influence of Rivers, came to identify himself primarily as a psychologist. McDougall was very quickly marginalized. There were two occasions when the promise of the Torres Strait began to be fulfilled: first, the reunion of Rivers, Myers, McDougall, and Seligman, all medically trained, at Maghull Hospital to help in the treatment of shell-shocked soldiers; second, Bartlett's attempt, early in his career, to establish a sociocultural psychology. However, the remarkable "academy" at Maghull was disbanded at the end of the war, and Bartlett, in his attempt to promote the "upstart subject" of psychology at Cambridge, increasingly came to distance his department from social and ethnological concerns. There is a neglected legacy of the Torres Strait expedition, the curious belief that the methods of experimental psychology, and indeed psychophysics, could (somehow) be foundational to the human sciences. This legacy has served both to suggest that psychology must have something to do with anthropology, while perpetually deferring any actual integration between the two disciplines.

Anthropology↗
PubMed1999

Children with autism experience problems with both objects and people.

Kanner (1943), in his classic account, described autism as a specific impairment in interpersonal relations which leaves the child's uses of objects relatively unaffected. This combination of the difficulties in relating to people and the supposedly "excellent" relations to objects figures centrally within many of the current theories of autism, which have had relatively little to say on the question of object use. This paper draws attention to evidence of widespread impairments in relating to objects, not only in interpersonal aspects of object use but also in early sensorimotor exploration and the functional and conventional uses of objects. In stressing these problems with objects, our purpose is not to downplay the social dimension of autism, but rather to highlight the reciprocal nature of the interactions between the child, other people, and objects. Given the evidence that other people play an important role in introducing objects to children, we propose that an impairment in interpersonal relations should itself lead us to expect corresponding disruption in the autistic child's use of objects. Conversely, an unusual use of objects is likely to manifest itself in disturbances in relating to other people, given the importance of a shared understanding and use of objects in facilitating interaction.

Autistic Disorder↗
PubMed1997

Visual perception of lifted weight from kinematic and static (photographic) displays.

Observers of patch-light videotape displays can reliably discriminate levels of lifted weight; accuracy of judgments sometimes approximates that achieved when the observers themselves lift weighted boxes. Results of 6 studies reveal impressive levels of visual weight discrimination based on static displays (photographs) of certain action phases sampled from videos of entire lifting-carrying events. Slow and controlled actions (e.g., walking, placing box on table) supported optimum weight discrimination for both photographic and video displays, whereas the action of lifting a box yielded high levels of discrimination only for video displays. Static and kinematic specification of dynamics, as well as the work by painters and photographers to depict humans and other animals in action, is discussed.

Adolescent↗