Evidence for Veridical Perceptual Mapping in Savant Syndrome: A Case Study

Background:  In a recent development of the enhanced perceptual functioning (EPF) hypothesis (Mottron & Bonnel, Bouvet, Samson, Burack, Heaton, submitted) we postulated that absolute pitch (i.e., the ability to name a pitch without a reference note) in autism has a more perceptual origin than in the typical population. We also argued that absolute pitch, savant syndrome (i.e., exceptional ability in a neurodevelopmentally atypical individual) and synaesthesia (i.e., perception of stimulation occurring indirectly via exposure to an apparently unrelated stimulus) share a common mechanism. We proposed that the mechanism of veridical mapping, a bottom-up associative mechanism between aspects of perceptual information that share a common structure, can account for the high prevalence of these phenomena in autism.

Objectives:  We present the case of an autistic savant person, F.C., 25 years old, who possesses absolute pitch as well as other savant abilities (mental and calendar calculation). First, as absolute pitch in the typical population does not involve superior auditory abilities (Miyazaki, 2004), we aimed to investigate if F.C.’s auditory abilities were different from those of a typical absolute pitch possessor. Second, we investigated the acquisition and development of his savant capacities in order to elucidate the mechanism of veridical mapping. Third, we also explored the links among absolute pitch, savant syndrome, and synaesthesia in F.C. and his family.

Methods:  A typical adult control group (n = 13, mean age = 21,1 ±6,2) and an absolute pitch typical participant (A.P.) were recruited for this study. Auditory tests with pure tones (frequency, intensity and duration discrimination) were conducted. The performance of F.C. and the AP control participant was compared to those of the control group. Clinical investigations were conducted in order to document the acquisition of F.C.’s savant abilities. Synaesthesia questionnaires were distributed to his family.

Results:  Compared to the typical controls, F.C. displayed superior performance in discriminating pure tone frequency and duration. These superior performances were not observed in A.P. We also observed that F.C. acquired absolute pitch by mapping days of the week with pitches and that he achieves mental calculation by transforming numbers into time (hours, minutes, seconds). Familial questionnaires revealed a high proportion of synaesthetes in his family (16 out of 24 individuals who filled out the questionnaire).

Conclusions:  We observed superior perceptual auditory ability in F.C., an autistic savant individual. We also found evidence for the cognitive mechanism of veridical mapping in the acquisition and development of his savant abilities. These results support the idea of a more perceptual absolute pitch in autism, but also the concept of veridical mapping as a common mechanism underlying absolute pitch, savant syndrome and synaesthesia. Further attention to links among these three phenomena is warranted, and there are implications with respect to genetic components and neural substrates.