Not all left/right judgment tasks elicit motor imagery; experimental investigations comparing judgment and movement times

Taylor, Matthew (2021). Not all left/right judgment tasks elicit motor imagery; experimental investigations comparing judgment and movement times. University of Birmingham. M.Sc.

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Abstract

Determining the laterality of an image depicting a disembodied hand (i.e. is it ‘left’ or ‘right’?) elicits motor imagery of the corresponding limb. In solving the task, we imagine our limb moving from its current position to the position shown in the image. This was most famously demonstrated by Parsons (1994) who showed that the time taken to make left/right judgments showed remarkable similarities with the time taken to move the limb to the same position.

Building on this established finding, the field of rehabilitation has adopted left/right judgment tasks (LRJTs) in the management of patients with chronic pain; the clinical value of the tasks residing in their ability to elicit motor imagery.

However, rather than limiting use to hand-based LRJTs, the field has developed new tasks involving different parts of the body and assumed that the same judgment process involving motor imagery occurs. Accordingly, LRJTs claiming to elicit motor imagery of the trunk, shoulder, neck and knee have been developed and are now sold commercially.

This thesis presents a series of experiments investigating the ability of different LRJTs to elicit motor imagery by building closely on Parsons’ (1994) influential study. It first examines a hand-based LRJT, replicating Parsons’ data for judgment and movement times (Chapter Two). Applying the same approach to a trunk-based LRJT revealed contrasting judgment and movement times; data were not consistent with the task eliciting motor imagery of trunk movements (Chapter Two). A second experiment examined judgment and movement times in response to shoulder-based images. Again, data were not consistent with shoulder-based LRJTs eliciting motor imagery of shoulder movements (Chapter 3). A final experiment also examined judgment and movement times for a shoulder-based task, but this time using commercially available images. Data were again inconsistent with the task eliciting motor imagery of shoulder movements and also draws attention to other problems with the task (Chapter 4).

Together, findings in the thesis provide clear theoretical and applied messages. Data confirm the ability of hand-based LRJTs to elicit motor imagery and support their use in clinical practice. However, data provide no support for the ability of trunk-based and shoulder-based LRJTs to elicit motor imagery of the corresponding body parts. It concludes that these newer forms of LRJT should be withdrawn.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

Supervisor(s):