Left/Right Judgment Task for the Chest Region, Part 2: Evidence for Mental Maneuvering in Performance During Chest Versus Shoulder Regions

Background: Left/right judgment tasks (LRJTs) theoretically require mental maneuvering one's body to reorient and match a viewed image. Mental maneuvering strategies may include spatial transformation and/or motor imagery. LRJT performance outcomes do not inherently distinguish between mental maneuvering strategies used to accomplish the task. Orientation difference (OD) describes the difference between the observer's position and the body orientation within an image. Evaluating whether LRJTs elicit mental maneuvering has traditionally been based upon the premise of an inverse linear relationship between LRJT performance and OD ("exact match" hypothesis). If true, larger ODs should lead to slower LRJT performance. Objectives: To evaluate the relationship between OD and chest and shoulder LRJT performance. Design: Observational, cohort study. Method: Associations between OD and LRJT accuracy and response time were evaluated in women with and without a history of unilateral breast cancer. Images from chest and shoulder LRJTs were categorized by various OD methods that assume more efficient (shortest path: OD(shortest path)) or less efficient (rotation by dimensions: (OD(rotation by dimensions)) participant mental maneuvering. Shoulder analyses also incorporated the angle between the arm and trunk (OD(shortest path + arm angle) and OD(rotation by dimensions + arm angle)). Results: Chest LRJT response time was most associated with OD(shortest path) (R-2 = 0.510). Shoulder LRJT response time was most associated with OD(rotation by dimensions + arm angle) (R-2 = 0.807). Both relationships were nonlinear. Discussion: Strong relationships between chest and shoulder LRJT and different OD models suggest these are discrete tasks that elicit mental maneuvering. The nonlinear nature of these relationships does not support the "exact match" hypothesis. Factors that can explain the remaining variance in LRJT performance need to be identified.