Comparative Punctate Pressure Sensitivity Assessment Reveals Human Tongue Is More Sensitive Than Fingertip

The tongue is what helps us participate in conversation and enjoy the food we eat. Yet, its sensitivity to tactile stimuli has not been characterized as completely as other systems, such as the fingertip. The purpose of this study was to determine the relative tactile sensitivity of the tongue versus the fingertip to provide insight into the tongue’s mechanosensitivity. Due to results from previous studies on roughness and point and edge detection, it was hypothesized that subjects would be better able to discriminate between punctate pressure stimuli with their tongue than their fingertip. Relative tactile sensitivity of the fingertip and the tongue was evaluated in healthy individuals (n = 30, 14m/16f, aged 19-28) using the forced-choice, up–down staircase method. In separate conditions, each subject was asked to discriminate between two punctate stimuli (F = 0.0044-0.010 g) when presented to their finger or their tongue using a Luneau Cochet-Bonnet Aesthesiometer (Western Ophthalmics Corporation, Lynnwood, WA). The force at the reversals minus the baseline force were averaged for each condition to obtain just noticeable difference (JND) thresholds and compared using a two-tailed, paired t-test (α = 0.05). The force needed to evoke a JND was significantly (p = 0.018) smaller in the tongue (0.0061 ± 0.0001 g) compared to the fingertip (0.0067 ± 0.0002 g). This agrees with the original hypothesis that people were better able to discriminate between stimuli with their tongues, therefore concluding that the tongue is more sensitive to punctate-pressure than the fingertip. While the reason for the tongue’s heightened sensitivity is unknown, it may reflect the closer proximity of mechanoreceptors to the lingual surface or it may indicate a greater density of mechanoreceptors on the tongue as compared to the fingertip allowing for easier discrimination of punctate stimuli. This experiment lays the foundation for other experiments comparing the sensitivity of the fingertip and the tongue, such as roughness and point-and-edge recognition, with the overall goal of determining the mechanisms behind texture perception associated with the consumption of foods and beverages.Will C. Hauk Endowment FundNo embargoAcademic Major: Food Science and Technolog