AUDITORY GENERALIZATION GRADIENTS FOR RESPONSE LATENCY IN THE MONKEY¹

Abstract

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)

Stimulus generalization in monkeys following discrimination training with gray stimuli

“…On the other hand, results like those of the present study have been obtained by Ernst, Engberg, and Thomas (1971) with pigeons, by Thomas and Setzer (1972) with rats and guinea pigs, and by Moody, Stebbins, and Iglauer (1971) using monkeys.…”

Stimulus Generalization, Discrimination Learning, and Peak Shift in Horses

“…Since Hanson's (1959) experiment, the peakshift phenomenon has been observed using many stimuli and many species. Researchers have successfully used the following stimulus dimensions: wavelengths of light (Blough, 1969;Thomas, 1962), visual intensity (Ernst, Engberg, & Thomas, 1971), auditory stimuli (Migler & Millenson, 1969;Moody, Stebbins, & Iglauer, 1971;Pierrel & Sherman, 1960;Thomas & Setzer, 1972), line-tilt dimensions (Bloomfield, 1967;Thomas & Lyons, 1968), floor-tilt dimensions (Riccio, Urda, & Thomas, 1966;Thomas, 1969), and object size (Brush et al, 1952;Jenkins et al, 1958). Most of this research has used rats and pigeons, but other organisms, including humans (Doll & Thomas, 1967), guinea pigs (Thomas & Setzer, 1972), goldfish (Ames & Yarczower, 1965), chickens (Rudolph & Honig, 1972), and monkeys (Moody et al, 1971), have also shown peak shift.…”

INTERACTIONS IN MULTIPLE SCHEDULES: NEGATIVE INDUCTION WITH SQUIRREL MONKEYS1

“…This effect cannot be interpreted unambiguously as contrast, however, since timeouts were response-produced, and Ferster (Experiment 5) also observed decreased responding when responses produced timeouts. Moody, Stebbins, and Iglauer (1971) found no evidence for a latency contrast effect (cf. Jenkins, 1961;Terrace, 1963) under a trial procedure in which lever-releasing responses by rhesus monkeys produced food in the presence of one but not another tone.…”