Scott_Jordan_Hemispheric lateralization and interhemispheric transfer asymmetries in manual stereognosis
Open Access
- Author:
- Scott, Jordan
- Area of Honors:
- Kinesiology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Robert L Sainburg, Thesis Supervisor
Jonas Rubenson, Thesis Honors Advisor - Keywords:
- stereognosis
hemisphere
hemispheric
tactile
interhemispheric
transfer
Jordan
Scott
lateralization
motor control
ipsilateral
contralateral - Abstract:
- Manual stereognosis, the ability to mentally perceive dimension and depth through tactile sensation and integration, is a complex process. Studies have reported inconsistent findings, due largely to different measures of performance. Since as early as 1906, the left hemisphere has been theorized to be dominant for stereognosis (Moll, 2017). Based on this hypothesis, I predicted the right-hand should show performance advantages in manual stereognosis tasks. A secondary exploratory goal assessed the effect of opposite hand exposure on performance. Participants of this study unimanually and blindly wielded 3D-printed cylinders of diameters ranging from 1 mm to 16 mm for three seconds. Without feedback, they selected which size cylinder they believed matched the one that they wielded. They completed 64 trials with one hand then switched hands for an additional 64 trials with the opposite hand. First exposure was defined as the hand used for the first 64 consecutive trials whereas second exposure referred to the hand used in the second round of 64 trials. MATLAB numeric computing software randomly assigned which hand went first exposure. We recorded error magnitude (difference in true cylinder diameter (mm) minus selected cylinder diameter) to be inversely related to stereognosis accuracy. The results did not fully match the hypothesis of left hemisphere dominance. Instead, our post hoc tests (Tukey HSD) showed lowest performance in the right hand, second exposure group (mean ± SE: -1.29 ± 0.48) and highest performance in the left hand, second exposure group (0.03 ± 0.59). The results of this study support previous studies which also found left hand (right hemisphere) improvements in stereognosis (Zaidel, 1998). I propose three possible explanations for the observed left hand improvement in the stereognostic task. First, the left hemisphere may have more ipsilateral control than the right hemisphere (Zaidel, 1998). Second, the left hemisphere may also help maintain working memory of the manipulated objects’ sensory information (Miquée, 2008; Stoeckel, 2004). Additionally, I hypothesize that the right hand has greater fine-motor control which leads to a better calibration and subsequently more accurate second exposure of the left hand.