Confusion percentages between Morse code signals. The scores are derived from confusion rates on 36 Morse code signals (26 for the alphabet; 10 for the numbers 0,...,9). Each Morse code signal is a sequence of up to five 'beeps'. The beeps can be short (0.05 sec) or long (0.15 sec), and, when there are two or more beeps in a signal, they are separated by periods of silence (0.05 sec).
Rothkopf asked 598 subjects to judge whether two signals, presented acoustically one after another, were the same or not. The values are the average percentages with which the answer 'Same!' was given in each combination of row stimulus i and column stimulus j, where either i or j was the first signal presented. The values are 1 minus the symmetrized confusion rates and are thus dissimilarities.
data(morse)
data(morse2)Symmetric and asymmetric dissimilarity matrices of 36 morse codes
The first dataset (morse) contains a symmetric version, the second dataset (morse2) the original asymmetric version.
Rothkopf, E. Z. (1957). A measure of stimulus similarity and errors in some paired-associate learning. Journal of Experimental Psychology, 53, 94-101.