Effects of trial duration on overall and momentary rates of maintained autoshaped keypecking: Choice and single-stimulus trials

Abstract

Pigeons were exposed to differentially cued autoshaping trials in which conditioned stimuli were followed by food after 6 or 14 sec. Average and momentary rates of keypecking were examined on two types of unreinforced test trials: single-stimulus probe trials and simultaneous choice trials, each 40 sec in duration. Rates averaged over the 40-sec test trials did not favor the cue associated with the shorter delay to food (the short-delay cue) on either type of test trial; however, average rates prior to the scheduled time of food delivery were reliably higher for the short-delay cue on choice trials. Momentary rates of keypecking during choice trials varied as a function of both cue and elapsed time from trial onset. At short elapsed trial times, rate ofpecking was higher for the short-delay cue, with this difference reversing at longer times. A reversal of the programmed relation between key color and delay to food presentation for 5 birds confirmed the generality of these findings. Implications of these data for models of Pavlovian conditioning and for methods of assessing conditioned response strength are discussed.As with other Pavlovian preparations, speed of acquisition under autoshaping procedures shows strong dependence upon parameters of reinforcement (Balsam, 1984; Gibbon, Baldock, Locurto, Gold, & Terrace, 1977; Gibbon, Farrell, Locurto, Duncan, & Terrace, 1980;Jenkins, Barnes, & Barerra, 1981). However, a more traditional measure of strength of keypeck responding-rate of maintained responding-shows less sensitivity to these variables (Balsam & Payne, 1979;Crawford, Steirn, & Pavlik, 1985;Gonzalez, 1974;Kay, Hemmes, & Brown, 1984;Lucas, Deich, & Wasserman, 1981; Newlin & LoLordo, 1976;O'Connell & Rashotte, 1982;Perkins et al., 1975).These findings challenge the comparability of autoshaped keypecking with other indexes of Pavlovian conditioning. Gibbon et al. (1980) addressed this issue, noting that measures of keypecking pertaining to the first peck of a trial generally behave similarly to more traditional preparations, whereas measures that include all of the pecks in a trial may not. In their study of autoshaped responding, strength of the first response (latency) in a trial increased with increasing probability of reinforceThis research was supported in part by Grant MH 39950-01 from the NationalInstituteof Mental Health, and by PSC/CUNY Grant 6-64350. We gratefully acknowledge the assistance of David Kay in the developmentof this project.Requests for reprintsmay be sent to NancyHemmes, Department of Psychology, Queens College-CUNY, Flushing, NY 11367. ment, while strength of subsequent responses (rate) varied inversely with reinforcement probability. Similar effects were reported by Picker and Poling (1982), who used a within-subjects design. Overall rates of responding on single-stimulus trials favored the partially reinforced cue; however, the locus of the first peck on choice trials revealed a clear preference for a cue associated with a 100% probability of reinforcement. This effect has also ...

Pairings of Ethanol Sipper With Food Induces Pavlovian Autoshaping of Ethanol Drinking in Rats: Evidence of Long-Term Retention and Effects of Sipper Duration

“…In the present study, for both groups, rate of drinking was negatively related to CS duration, and this relationship between CR performance and CS duration has been widely reported by Pavlovian investigators (for reviews, see Mackintosh, 1974;Killeen, 1984) employing a wide range of procedures, including fear conditioning (Odling-Smee, 1975;Burkhardt and Ayres, 1979;Ishii, 1991;Rosas and Alonso, 1997), conditioned enhancement and positive conditioned suppression (Meltzer, 1986), conditioned odour aversion in rats (Rudy and Cheatle, 1978), and conditioning of heart rate and body temperature with morphine (Schwarz-Stevens and Cunningham, 1994). In addition, the negative relationship between CR performance and CS duration (for reviews, see Gibbon and Balsam, 1981;Jenkins et al, 1981;Killeen, 1984) has also been reported by numerous autoshaping investigators employing pigeons (Balsam et al, 1978;Gibbon and Balsam, 1981;Balsam and Gibbon, 1982;Balsam, 1984;Hemmes and Brown, 1990) and rats (Locurto et al, 1981;Kirkpatrick and Church, 2000).…”

Sign and goal tracking during delay and trace autoshaping in pigeons

“…Since that pattern developed within the CS segment of the trial, its growth is not attributable simply to CS offset. Rather, it could reflect the sort of temporal control familiar in other Pavlovian preparations, though generally not in autoshaped keypecking (see Hemmes et al, 1990). In that case, a function of a trace CS may be to start the internal clockbased timing of the CS-US interval (Church, 1984).…”

“…Even the widely studied autoshaped keypeck response does not always yield law-. ful data (Hemmes, Brown, & Cabeza de Vaca, 1990;Picker & Poling, 1982).…”

A comparison of empirical and theoretical explanations of temporal discrimination.

“…As in the present experiment, both stimuli remained on after the delivery of reinforcement. This duration was the same for both stimuli (40 s Hemmes et al, 1990), keeping the rate of reinforcement during each stimuli constant. Hemmes et al observed no effects of the delay to reinforcement on the overall rate of responding (rate during the 40 s of stimulus presentation), but observed a different pattern of responding during each stimulus that was a function of the delay to reinforcement.…”

“…It is well know that rats can learn to discriminate multiple intervals whether the intervals are signaled by different stimuli (Guilhardi & Church, 2004, 2005; Hemmes, Brown, & Cabeza de Vaca, 1990) or by the same stimulus (Catania & Reynolds, 1968; Platt & Davis, 1983), even if these intervals are trained simultaneously within a session. This ability to learn multiple discriminations simultaneously is reflected in most theories, such as scalar timing theory, learning to time theory, and modular theory, with the assumption of independent memories for each of the temporal discriminations trained.…”