AUDITORY DISCRIMINATION: A THREE‐VARIABLE ANALYSIS OF INTENSITY EFFECTS 1

Two monkeys were trained to press and hold a response key in the presence of a light and to release it at the onset of a pure tone. Initially, all responses with latencies shorter than 1 sec were reinforced without regard to the frequency of the pure tone, and the intensity of the pure tone that resulted in equal latencies at each frequency was determined. The second stage of the experiment consisted of discrimination training, during which releases to one pure-tone frequency (positive stimulus) were reinforced and releases to a second frequency (negative stimulus) were extinguished. Median latencies to the negative stimulus slowly increased as did the variability of the latency distribution for the negative stimulus. There was no evidence of a concurrent decrease in latencies to the positive stimulus indicative of behavioral contrast. The third part of the experiment consisted of determining maintained generalization gradients by increasing the number of nonreinforcement stimuli. The gradients that eventually resulted showed approximately equal latencies to all frequencies of the negative stimulus and shorter latencies to the positive stimulus frequency.The use of sophisticated behavioral techniques in recent years has added a great deal to knowledge of the stimulus control of operant behavior. Much of this knowledge, however, is based on observations of a single dependent variable: rate of responding. Although rate is widely accepted, in many instances it does not adequately specify behavior. For example, Blough (1963) (e.g., Terrace, 1963a, b;Farmer, Schoenfeld, and Harris, 1966;Winograd, Cohen, and Cole, 1965;Jenkins, 1961). Two problems are frequently encountered when the latency measure is used. The first is that suitable contingencies are not included to control where the animal is in the chamber at the moment of stimulus onset. The inclusion of key approach time in the latency increases variability and may hide the latency differences related to the value of the stimulus. The second problem is that no latency can be measured if the animal fails to respond. Since well-trained subjects seldom respond to the negative stimulus (S-), few latencies enter into the S-sample. Latency is frequently discarded as a useful dependent 105 197 1, 16, 105-11 1 NUMBER I (J ULY)

Section: And Discussionmentioning

confidence: 78%

AUDITORY GENERALIZATION GRADIENTS FOR RESPONSE LATENCY IN THE MONKEY¹

Moody¹,

Stebbins²,

Iglauer³

1971

“…A large body of literature, using both between-and within-groups designs, lhas demonstrated that as the intensity of a stimulus is increased, the level of response maintained by that stimulus is also increased (Gray, 1965;Grice, 1968;Pierrel, Sherman, Blue, and Hegge, 1970 …”

mentioning

confidence: 99%

COMPOUNDING OF DISCRIMINATIVE STIMULI FROM THE SAME AND DIFFERENT SENSORY MODALITIES¹

Miller¹

1971

Rats' responding was maintained by fixed-interval schedules of reinforcement in the presence of a tone or two separate lights. The lights were either of low, moderate, or high intensity. Compounds of these single discriminative stimuli each maintained a greater frequency of response than did the single stimuli, and the compound composed of stimuli from different sensory modalities (light + tone) maintained a greater level of responding than did the compound composed of stimuli from the same sensory modality (light + light). Combining lights of different intensity had no differential effect on responding. However, in the second experiment, a compound composed of a light and a tone, each of greater intensity than the light and tone of another compound, initially maintained a higher frequency of response, demonstrating intensity effects during stimulus compounding when the increase in intensity occurs through the component stimuli. This intensity effect, however, was only transitory.

“…Still, it is possible that variations of our procedure might reveal a dynamism effect. Pierrel, Sherman, Hegge, and Blue (1970) suggested that dynamism may habituate with training. Each of our rats ran more than 500,000 trials over the course of training and testing.…”

Section: Discussionmentioning

confidence: 99%

Comparison of Yes‐no and Latency Measures of Auditory Intensity Discrimination

Green¹,

Terman²,

Terman³

1979

Rats discriminated auditory intensity differences of sinusoids at 3.0 kilohertz in a go/no-go signal detection procedure. Responses to the signal (hits) were reinforced with electrical brain stimulation, and misses produced a brief timeout. On intermixed noise trials, withholding of responses (correct rejections) was reinforced, and false alarms produced the timeout. In two test conditions, the signal was either the louder (100 decibels) or softer (90, 93, 96, or 99 decibels) of the pair of intensities presented within a set of trials. Each animal was first trained with signal value louder or softer, and reversed for the second condition so that the former noise value served as signal. Hits showed shorter latencies than false alarms, regardless of the relative intensity of signal and noise, and the nmagnitude of differentiation was proportional to signal-noise separation. Both hits and false alarms showed longer latencies as the discrimination became more difficult. Isosensitivity contours derived from the latencies showed close similarity across conditions; in comparison, the yes-no measure of detectability, d', showed greater variability. The similarity of latency differentiation across louder and softer signal conditions supports a detection model in which the ob.erver's judgment is controlled by the distance of sensory effect from criterion on each trial, as opposed to the loudness of the tones per se.