Individual differences in the sensitivity to pitch direction

Abstract

It is commonly assumed that one can always assign a direction-upward or downward-to a percept of pitch change. The present study shows that this is true for some, but not all, listeners. Frequency difference limens (FDLs, in cents) for pure tones roved in frequency were measured in two conditions. In one condition, the task was to detect frequency changes; in the other condition, the task was to identify the direction of frequency changes. For three listeners, the identification FDL was about 1.5 times smaller than the detection FDL, as predicted (counterintuitively) by signal detection theory under the assumption that performance in the two conditions was limited by one and the same internal noise. For three other listeners, however, the identification FDL was much larger than the detection FDL. The latter listeners had relatively high detection FDLs. They had no difficulty in identifying the direction of just-detectable changes in intensity, or in the frequency of amplitude modulation. Their difficulty in perceiving the direction of small frequency/pitch changes showed up not only when the task required absolute judgments of direction, but also when the directions of two successive frequency changes had to be judged as identical or different.

Stimulus uncertainty and insensitivity to pitch-change direction

“…Based on earlier findings, which suggest that the human auditory system contains neural populations that are selectively sensitive to the direction of small frequency changes ͑Demany and Ramos, 2005; Demany et al, 2009b͒ Semal andDemany, ͑2006͒ proposed that such frequency-shift detectors ͑FSDs͒ may not respond to small shifts in the brains of direction-impaired listeners. The result that insensitivity to pitch-change direction is greatly reduced or eliminated when wide frequency roving is not used suggests either that this explanation is incorrect, or that when the stimuli are not roved widely in frequency, listeners' ability to identify pitchchange direction no longer relies on FSDs.…”

“…Clearly these experiments require listeners to be-and indeed demonstrate that they often are-sensitive to the direction or sign of very small frequency changes. However, three more recent studies have suggested that in certain circumstances some listeners can detect the presence of a small frequency difference, but are unable to identify the direction of the resulting percept ͑Johnsrude et al, 2000; Tramo et al, 2002;Semal and Demany, 2006͒. Two of the studies cited above involved listeners with cortical lesions. Johnsrude et al ͑2000͒ tested patients with unilateral temporal lobe excisions and healthy controls using two frequency discrimination tasks: a two-interval, twoalternative forced-choice ͑2I-2AFC͒ task similar to those used in classic studies of frequency discrimination, and a same-different ͑SD͒ task in which the second tone was equiprobably identical to or higher in frequency than the first tone.…”

A general formula for computing maximum proportion correct scores in various psychophysical paradigms with arbitrary probability distributions of stimulus observations

“…Specifically, the participant is now asked to indicate whether the pair containing one A and one B stimulus was AB or BA. Although it is superficially similar to the basic 4IAX paradigm, the 4IAX, ABversus-BA paradigm involves a substantially different underlying decision strategy and a completely different relationship between d′ and Pc (Micheyl & Dai, 2009;Semal & Demany, 2006). For these two dual-pair paradigms, Pc can be determined following an approach similar to the one that we used for the two-interval same-different paradigm.…”

“…In one version-namely the basic dual-pair paradigm, which is commonly abbreviated 4IAX (for four-interval, samedifferent)-the task of the participant is to indicate which pair contains stimuli that are different (AB or BA vs. AA or BB). This version of the paradigm is useful in experiments that aim to measure performance in stimulus discrimination, or change detection Semal & Demany, 2006). In the second version-namely the 4IAX, AB-versus-BA paradigmthe exact same stimulus design can be used to explore a different ability of the participant, the ability to identify the direction of changes (i.e., AB vs. BA); all that the experimenter needs to do is to change the instructions.…”

“…Yet another example of situations in which the Gaussian assumption is inadequate relates to experiments in which a stimulus feature, which could provide an unwanted cue for task performance, is randomly perturbed (or "roved") across observation intervals within a trial, or across trials, in order to limit its use by participants. Examples of this abound in both the auditory-perception literature (e.g., Berg & Green, 1990;Berliner & Durlach, 1973;Dai, 1994Dai, , 2008Dai & Green, 1993;Dai, Nguyen, & Green, 1995Hall & Fernandes, 1983;Henning, 1966;Jesteadt & Bilger, 1974;Kidd, Mason, Brantley, & Owen, 1989;Kidd, Mason, Uchanski, Brantley, & Shah, 1991;Micheyl, Divis, Wrobleski, & Oxenham, 2010;Moore & Glasberg, 1989;Oxenham & Buus, 2000;Semal & Demany, 2006;Spiegel, Picardi, & Green, 1981;Strickland & Dhar, 2000) and the visual-perception literature (e.g., Danilova & Mollon, 2010;Dannemiller & Stephens, 1998;Morgan, 2005;Nachmias, 1999Nachmias, , 2002Regan & Hamstra, 1991, 1992Webster, De Valois, & Switkes, 1990). In such "roving" experiments, the experimenter must determine the size of the roving range necessary to ensure that the highest Pc that participants can achieve using the unwanted cue is below a predefined target (e.g., 60 % correct).…”