Haptic signals of texture while eating a food. Multisensory cognition as interacting discriminations from norm.

This study started to characterise the cognitive processes by which physical effects on the senses are transformed into quantitative judgments about conceptualised aspects of a food. Using words provided by assessors, discriminations of a shortbread biscuit's fracturing patterns during eating from each assessor's internal norm were measured for the initial steps of denting, biting and crushing the material. The haptic concept of dentability (lack of crispness) often discriminated cracks in the biscuit that were the lowest in force, but was also sensitive to high-force cracks and frequency of cracks. How hard it was to bite through the sample was most often sensitive to the force of snapping the biscuit and to high-force cracks. Frequency of cracks usually dominated how "crunchy" the biscuits were rated to be. Interactions among the normed discrimination functions accounted for judgments of overall distance from the personal norm for the complex overall texture of the biscuit and revealed each assessor's cognitive strategies in reaching those integrative judgments. Use of the haptic concepts tended to shift mentation from control of the integrative texture ratings directly by sensory stimulation to the relating of those concepts to the sensed patterns, i.e., to describing texture.