Franklin Henry is generally acknowledged as the “Father of Motor Behavior Research.” There is little doubt that Henry's ‘memory drum' theory paper (Henry & Rogers, 1960) was one of the most influential studies of the response programming stage of information processing. In fact, this paper is the most–cited motor behavior study ever published in the Research Quarterly. However, few people know that there is a critical error in the paper, namely in the description of the “C” response. The “C” response was the most complicated of the three movements studied, which gave rise to the classic finding that longer reaction latencies were associated with more complex movement responses (the response complexity effect). Even Dr. Henry himself was unaware of the error for nearly 20 years after the paper's publication. The purpose of my presentation is to reveal the story behind the mystery of the “C” response. The data come in the form of the original 1960 paper which describes the “C” response, and a paper by Howell (1953) which contains an illustration and description of the apparatus used in 1960. It is clear that the 1960 directions for executing the “C” response do not match the 1953 illustration of the apparatus. I will also share several personal letters from Dr. Henry dating back to 1979, when the error was first discovered, and continuing through 1986. In one particular letter, Henry revealed to me that during his entire scholarly life he suffered from a mild and specific form of aphasia, manifested by reversals of words. Usually, his reversals were corrected before printing, but in the case of the ‘memory drum' theory paper they were not. Such a revelation makes the career of this remarkable scholar even more remarkable.Keyword(s): physical activity, research