The use of the titrating delayed matching-to-sample procedure for analyzing drug effects

Abstract

A titrating delayed matching-to-sample (TDMTS) procedure, in which the delay between the sample and comparison stimuli depends on the subject's performance, was used to assess the effects of 0.5 mg/kg of haloperidol in pigeons. The results showed that the decrease in the limit of delay sustained by the subjects in the drug condition could not be attributed to drug effects on short-term memory, because the limit of delay measure was confounded by the effect of the drug on psychomotor responding. Implications of the use of the TDMTS procedure are discussed.Matching-to-sample (MTS) is an experimental procedure that has been used to assess the effects of drugs on stimulus control. In MTS, a trial begins with the presentation of a sample stimulus. After an appropriate response is made, two or more comparison stimuli are presented, one of which is identical to the sample stimulus. To obtain a reinforcer, the subject must respond to the comparison stimulus that' 'matches the sample" (McMillan, 1981).When a delay is interpolated between the sample and comparison stimuli (delayed matching-to-sample, DMTS), the procedure becomes useful for the study of both concept formation and short-tenn memory (STM) in animals (McMillan, 1981). The DMTS paradigm has two advantages in the study of STM. First, it minimizes the influence of peripheral mediating responses, and second, DMTS tasks may employ exteroceptive stimuli that permit a rigorous manipulation of stimulus parameters and precise specification of stimulus and retention interval duration (Pontecorvo, 1983).Perfonnance under DMTS, across a variety of species, shows that with increases in the delay interval, there is a corresponding decrease in the accuracy of the animals' perfonnance. Thompson (1978) has suggested that DMTS might be more sensitive to drug effects than is MTS because DMTS is presumably under weaker control by the sample stimulus. Stimulus control by the sample stimulus should weaken progressively as the delay increases. Therefore, under DMTS, drug effects might be seen at This report is based on data from a project submitted by the first author in partial fulfillment of the requirements for a master's degree in psychology. The authors acknowledge the assistance of the following pe0-ple: Chris van Halewyn for writing the computer program, Ijan Beveridge for his care of the animals, and Robin Phillips for his assistance in the preparation of this manuscript. Requests for reprints should be addressed to L. Woodward, Department of Psychology, University of Canterbury, Christchurch, New Zealand. doses lower than those at which effects appear under MTS, or larger drug effects may be seen at the same dose as the delay increases (McMillan, 1981). The DMTS procedure has proved useful in the assessment of the effects of a variety of drugs (Heise & Milar, 1984;Thompson, 1978).In the standard DMTS procedure, the delay values at which the subjects work are usually arbitrarily set by the experimenter. One variation of the DMTS procedure is the titrating DMTS procedure (TD...

Titrating‐delay Matching‐to‐sample in the Pigeon

“…Each TDMTS session can, however, be programmed to start with a zero delay, or any other value for that matter. Indeed, several of the studies discussed above programmed daily sessions to begin with a zero delay (e.g., Jarrard & Moise, 1970; Poling et al, 1996; Woodward et al, 1986). Therefore, the purpose of Experiment 2 was two‐fold.…”

“…This variable, like the two investigated above, has also varied throughout the literature. For example, some have used a 0.5‐s step size (e.g., Woodward et al, 1986), 1 s (e.g., Cumming & Berryman, 1965), 2 s (e.g., Ferraro et al, 1971), or a progressive step size (e.g., Scheckel, 1965). One potential advantage of programming a larger step size is the opportunity to observe a larger within‐session range of titration; that is, allowing the subject more movement in either direction within‐session.…”

“…The TDMTS procedure has also been employed to study the relation between pharmacological agents and behavior. Research on drug effects under this procedure, conducted with pigeons, nonhuman primates, and humans, have included the effects of a variety of drugs including caffeine, cocaine, d ‐amphetamine, diazepam, ethanol, linopirdine, morphine, nicotine, pentobarbital, phencyclidine, scopolamine, and thioridazine (Buccafusco, Terry, & Murdock, 2002; Buccafusco, Terry, Goren, & Blaugrun, 2003; Dayer, Baron, Light, & Wenger, 2000; Hudzik & Wenger, 1993; Nordholm, Moore, & Wenger, 1995; Wenger & Kimball, 1992; Wenger & Wright, 1990; Wenger, Hudzik, & Wright, 1993; Wenger, Hudzik, Moore, & Wright, 1996; Woodward, Watson, Blampied, & Singh, 1986; Wysocki, Fuqua, Davis, & Breuning, 1981). As one might imagine, effects on titrated delay values vary across drugs, but like pharmacological studies with DMTS procedures, systematic dose‐related effects on performance are usually observed.…”