Tactile Spatial Acuity from Childhood into Adulthood

Measurement of human tactile spatial acuity – the ability to perceive the fine spatial structure of surfaces contacting our fingertips – provides a valuable tool for probing both the peripheral and central nervous system. However, measures of tactile spatial acuity have long been plagued by a prodigious amount of variability present between individuals in their sense of touch. Previously proposed sources of variability include sex, and age; here we propose a novel source of variability – fingertip size. Building upon anatomical research, we hypothesize that mechanoreceptors are more sparsely distributed in larger fingers. In this thesis, I provide empirical and theoretical support for the hypothesis that fingertip growth from childhood into adulthood sets up an apparent sex difference in human tactile spatial acuity during young adulthood (Chapter 2), and also predicts changes in acuity more strongly than does age over development (Chapter 3). To further understand how fingertip size could limit an individual's tactile spatial acuity, we develop an ideal observer model using neurophysiological data collected by other labs (Chapter 4). In summary, this research provides support for a novel source of variability in the sense of touch: one that parsimoniously explains an apparent sex difference, and helps clarify the source of changes in tactile spatial acuity occurring with age during childhood.