Discriminability, loudness, and masking in the rat (Rattus norvegicus): A confirmation and extension.

Abstract

In Experiment 1, rats discriminated between two sound pressure levels (SPL) of a pure tone: standard (STD) SPLs of 84 and 74 dB and comparison (CO) SPLs 4, 14, and 24 dB below STD were tested in quiet and 60 dB noise at 4 and 12.5 kHz (24 conditions). The decibel difference between STD and CO accounted for only 43.52% of the variance in the signal detection measure of sensitivity, d', across conditions, whereas the loudness difference (LD = STD0.35 - CO0.35) accounted for 89.82% of the variance in d'. These results confirm and extend previous observations that: (a) equal decibel differences are not equally discriminable; (b) loudness for the rat increases as a power function of SPL with an exponent of 0.35: and (c) masked loudness is a linear function of loudness in quiet. In Experiment 2, the assumptions of normal distribution and equal variance implicit in the use of the d' measure were examined. Receiver operating characteristic curves that were well approximated by straight lines of unit slope in normal-normal coordinates were obtained and thereby validated the use of d' in Experiment 1.

Loudness bisection and masking in the rat (Rattus norvegicus).

“…Our bisection data is consistent with a power function formulation, although the exponents from discriminability data for the rat appear to be somewhat lower (see Raslear, 1989, Table 4) than what was obtained here. Raslear (1989) also concluded that perceived loudness is properly measured on an interval scale. This conclusion was based on the fact that masking noise produces a linear transformation of scale for loudness.…”

“…The primary purpose of our experiment was to provide a formal test of NFS for auditory intensity bisection with animals. Although discriminability data has been widely used for psychophysical scaling with humans and animals (see Raslear, 1989), an easily tested measurement system for discrimination methods of scaling is not available. Thus, the comparison of human and animal loudness perception in those methods is dependent on the assumption that the measurement systems used with various species are valid and commensurate (see Raslear, 1989).…”

“…Although discriminability data has been widely used for psychophysical scaling with humans and animals (see Raslear, 1989), an easily tested measurement system for discrimination methods of scaling is not available. Thus, the comparison of human and animal loudness perception in those methods is dependent on the assumption that the measurement systems used with various species are valid and commensurate (see Raslear, 1989). The establishment of a valid scale with an alternative method (i.e., bisection) would provide an additional benchmark by which to evaluate such cross-species comparisons.…”

“…A major problem in animal psychophysics is the construction of psychophysical scales that are comparable with those in use with human subjects. Whereas the majority of human psychophysical scaling work depends heavily on verbal behaviors that are difficult to adapt to nonverbal species (e.g., magnitude estimation and category scaling), the small literature on scaling with animals has emphasized the construction of scales from discrimination data (e.g., Pierrel-Sorrentino & Raslear, 1980; Raslear, 1989; Raslear, Pierrel-Sorrentino, & Rudnick, 1983). Because there is a reasonable body of literature on sensory discrimination in humans and psychophysical scales can be constructed from that data (Parker & Schneider, 1980), it may seem that comparable sensory scales could be constructed from animal data.…”

Simultaneous Auditory Discrimination

“…In the presence of a 256-Hz tone entering the left alley was reinforced, and in the presence of a 320-Hz tone entering the right alley was reinforced. Hunter (1914,1915) extended Johnson's work, and the go-right/go-left procedure with successive stimulus presentation has been used extensively (e.g., Dewson, 1964;Harrison, 1983;Henry, 1936;Lawicka, 1969;Muenzinger & Gentry, 1931;Pennington, 1938;Raslear, 1989;Thuma, 1932). The go/ no-go procedure, in which the subject is required to make a response in the presence of one sound and not to respond in the presence of a second sound, has also been used extensively in the study of auditory discrimination (Lawicka, 1964(Lawicka, , 1969Lawicka, Mishkin, & Rosvold, 1975;May, Moody, & Stebbins, 1989;Neill & Harrison, 1987;Shepherd, 1914), and D'Amato and Colombo (1985) developed a go/ no-go auditory matching-to-sample procedure.…”