Data indicates that the effect of familiar size is effective for objects larger in size than the objects that the subjects were familiar with. This effect did not take place when an object smaller than the familiar object was presented. To test Lawrence and Yonas’ (2023) hypothesis, a replication of the study was conducted with the addition of two more experimental groups. The familiar subjects were all allowed to touch the object in Lawrence and Yonas’ (2023) study, so groups were added in which participants were not permitted to touch the objects. Two groups were added: one group learned about the size of objects at a distance that would match the visual angles of the smaller objects, and one group that were familiarized with a visual angle matching the larger objects. This made it possible to test the effects of tactile and kinesthetic information on the process of familiarization and its effect on familiar size.

The brain uses the somatosensory system to interact with the environment and control movements. Additionally, many movement disorders are associated with deficits in the somatosensory sensory system. Thus, understanding the somatosensory system is essential for developing treatments for movement disorders. Previous studies have extensively examined the role of the somatosensory system in controlling the lower and upper extremities; however, little is known about the contributions of the orofacial somatosensory system. The overall goal of this study was to determine factors that influence the sensitivity of the orofacial somatosensory system. To measure the somatosensory system's sensitivity, transcutaneous electrical current stimulation was applied to the skin overlaying the trigeminal nerve on the lower portion of the face. After applying stimulation, participants' sensitivity was determined through the detection of the electrical stimuli (i.e., perceptual threshold). The data analysis focused on the impact of (1) stimulation parameters, (2) electrode placement, and (3) motor tasks on the perceptual threshold. The results showed that, as expected, stimulation parameters (such as stimulation frequency and duration) influenced perceptual thresholds. However, electrode placement (left vs. right side of the face) and motor tasks (lip contraction vs. rest) did not influence perceptual thresholds. Overall, these findings have important implications for designing and developing therapeutic neuromodulation techniques based on trigeminal nerve stimulation.