Mahurin Honors College Capstone Experience/Thesis Projects


Psychological Sciences

Document Type



Object shape perception is fundamentally important for daily life. It has been suggested (e.g., Gibson, 1962) that the visual and haptic modalities are equivalent with regards to the ability to perceive shape. Norman et al. (2012) showed that visual and haptic shape discrimination accuracies are indeed comparable. Craddock and Lawson (2009) found that haptic shape discrimination performance was adversely affected by a size change. However, this result was obtained for man-made objects (i.e., bathtubs and benches). The purpose of the current investigation was to determine whether size changes also reduce haptic shape discrimination accuracy for naturally-shaped objects. On any given trial, adult participants haptically explored two bell pepper replicas and judged whether they possessed the same or different shapes. In one condition, the two explored objects were of the same overall size, while in two other conditions, the objects differed in size (either by smaller or larger amounts). The results indicated that while size changes do have negative effects upon haptic shape discrimination, larger magnitude size changes do not hurt performance any more than smaller size changes. Although visual shape discrimination is not appreciably affected by size change (e.g., Landau & Leyton, 1999; Norman, Swindle, Jennings, Mullins, & Beers, 2009) and haptic shape discrimination of man-made objects is adversely affected by size change (Craddock & Lawson, 2009), the current results demonstrate that the haptic system can indeed tolerate some object size change without impairment in human discrimination performance.

Advisor(s) or Committee Chair

Dr. J. Farley Norman


Other Physics | Other Psychology | Psychology