Original Articles

Calendar calculating in savants with autism and healthy calendar calculators

A. M. Dubischar-Krivec^a1 c1, N. Neumann^a1, F. Poustka^a2, C. Braun^a1, N. Birbaumer^a1a3 and S. Bölte^a2

^a1 Institute of Medical Psychology and Behavioral Neurobiology, Eberhard Karls University, Tübingen, Germany

^a2 Department of Child and Adolescent Psychiatry and Psychotherapy, J. W. Goethe University, Frankfurt, Germany

^a3 Istituto di Ricovero e Cura a Carattere Scientifico (IRCSS), Ospedale San Camillo, Venezia Lido, Italy

Abstract

Background Calendar calculation is the ability to quickly name the day that a given date falls on. Previous research has suggested that savant calendar calculation is based on rote memory and the use of rule-based arithmetic skills. The objective of this study was to identify the cognitive processes that distinguish calendar calculation in savant individuals from healthy calendar calculators.

Method Savant calendar calculators with autism (ACC, n=3), healthy calendar calculators (HCC, n=3), non-savant subjects with autism (n=6) and healthy calendar calculator laymen (n=18) were included in the study. All participants calculated dates of the present (current month). In addition, ACC and HCC also calculated dates of the past and future 50 years.

Results ACC showed shorter reaction times and fewer errors than HCC and non-savant subjects with autism, and significantly fewer errors than healthy calendar calculator laymen when calculating dates of the present. Moreover, ACC performed faster and more accurate than HCC regarding past dates. However, no differences between ACC and HCC were detected for future date calculation.

Conclusions The findings may imply distinct calendar calculation strategies in ACC and HCC, with HCC relying on calendar regularities for all types of dates and an involvement of (rote) memory in ACC when processing dates of the past and the present.

(Received September 19 2006)

(Revised August 18 2008)

(Accepted September 04 2008)

(Online publication October 22 2008)

Key Words:

• Autistic intelligence;
• cognition;
• extraordinary abilities;
• pervasive developmental disorders;
• savant syndrome

Correspondence:

^c1 Address for correspondence: A. M. Dubischar-Krivec, Ph.D, Institute of Medical Psychology and Behavioral Neurobiology, Gartenstraße 29, D-72074 Tübingen, Germany. (Email: anna.dubischar@uni-tuebingen.de)