An efficient continuous-tone procedure for the study of frequency discrimination

This paper describes a method of gathering experimental data for the study of frequency discrimination. The method is efficient in terms of participant time, is easy to deploy on an online platform to gather behavioral responses, and allows simultaneous measurement of brain activity without contamination from onset responses. The participant hears a continuous tone within each block, with frequency steps at predetermined intervals, and is invited to respond "up" or "down" to these steps by pressing one of two keys. The magnitude of the steps varies according to a predetermined schedule (constant-stimuli, not adaptive) from large (easy) to small (hard), and the discrimination threshold is derived from a psychometric function fitted to the responses to this sequence. Comparison with earlier published procedures shows that the new method yields comparable thresholds, albeit less variable and slightly lower, and thus presumably closer to sensory limits.