Same-different reaction times to pairs of nonsense syllables

Abstract

Reaction times were measured for the same-different discrimination of selected pairs of VC nonsense syllables in four normally hearing subjects. Five phonemes were selected as standards for experimental study and each of these standards was contrasted with four phonemes. Lists contained equal numbers of same and different presentations. Syllables were stored digitally and then trimmed to a uniform length of 335 msec prior to recording. Intersyllable interval was 750 msec. Results showed that the error rate which resulted from calling same stimuli different was relatively constant at about 0.05. The error rate for calling different stimuli same was found to vary for specific phonemic comparisons and was directly related to the size of the difference between different and same RTs and inversely related to d′, to the criterion measure β, and to the number of features (Wickelgren, 1966) by which the pair contrasted. The results are related to a theory of stimulus codability and difficulty as determinants of the relative size of same and different RTs. [Supported by Public Health Service Award NS-7790.]