Intertrial interval effects in pavlovian serial feature positive discriminations

Abstract

The effects of the intertrial interval (lTI) on learning and performance in Pavlovian appetitive serial feature positive (SFP) discriminations were examined in three experiments with rats, Withlonger ITIs, acquisition was more rapid, and there was less transfer of the feature's behavioral control to a separately trained target cue, suggesting that longer ITIs encouraged the use of an occasion setting strategy. Behavior was also affected by discrimination-specific ITIs. Rats were trained with two SFP discriminations. The overall ITI was held constant, but the intervals between trials of one discrimination were varied by intermixing different numbers of trials from the other discrimination. Learning was more rapid when the intervals between trials of a single discrimination were longer. A sequential analyses showed that performance on a trial was impaired when it was preceded by a trial that included the same target cue but with the opposite trial outcome. The results are discussed in the frameworks of proactive interference effects and deletion-comparator processes (Cooper, Aronson, Balsam, & Gibbon, 1990.) Performance in learning tasks is often affected by the spacing oftrials. Longer intertrial intervals (ITIs) encourage superior performance in a variety of tasks, including, for example, simple nondiscriminative Pavlovian conditioning (e.g., Gormezano & Moore, 1969;Spence & Norris, 1950), delayed matching-to-sample (e.g., Grant, 1975), and operant serial feature positive discrimination training (Holland, 1995). Moreover, many researchers have found that the ITI can affect within-trial interstimuIus interval functions as well. For example, conditioning can occur with longer intervals between the onsets of the conditioned stimulus (CS) and unconditioned stimulus (US) if those CS-US pairings are separated by long ITIs than when they are massed in time (Gibbon, Baldock, Locurto, Gold, & Terrace, 1977). In fact, Gibbon et al. and other investigators (e.g., Roberts & Kraemer, 1982) have claimed that it is not the CS-US or intertrial intervals themselves that determines the amount of conditioning, but rather their ratio.Holland (1995) examined the effects ofITI on the acquisition ofoperant serial feature positive discrimination learning, in which responding during a target cue was only reinforced when that target was preceded by another, feature cue (feature~target+/target-). Acquisition of the discrimination was more rapid the longer the ITI. Furthermore, longer ITIs also seemed to favor the use of an occasion setting strategy (Holland, 1992) in solving that discrimination. That is, with shorter ITIs, the feature was This research was supported in part by grants from the National Science Foundation and the National Institute of Mental Health. The author thanks Marie Crock, Corey McNamee, and John Chen for technical assistance. Correspondence should be addressed to P. C. Holland, Department of Psychology: Experimental, Duke University, Box 90086, Durham, NC 27708-0086 (e-mail: pch@duke.edu). more likely to exert dire...

Acquisition and extinction of facilitation in the C57BL/6J mouse

“…Other studies have shown that the acquisition of Pavlovian conditioning may be improved with longer ITIs (Frey & Ross, 1968;Gibbon, Baldock, Locurto, Gold, & Terrace, 1977;Kehoe & Gormezano, 1974) and fewer trials per day (Kehoe & Gormezano, 1974). Similar benefits of trial spacing have been documented for the acquisition of serial feature-positive discriminations (Holland, 1995(Holland, , 1999. The possibility should not be discounted that a similar beneficial effect may occur for extinction and that, with parameters more similar to those used in the present experiments, Rescorla (1986a) and Holland (1989b) might have obtained a reduced enhancement effect.…”

Trial and intertrial durations in appetitive conditioning in rats

“…Previous studies with this conditioning preparation also showed that 240-sec Is supported better learning than did shorter Is (e.g., Holland, 1995Holland, , 1999Holland & Morell, 1996), although those same studies showed that 480-sec Is supported either equivalent (Holland, 1995) or superior (Holland & Morell, 1996) learning. It is possible that the relation observed in Experiment 2 reflects a tradeoff between independent facilitatory effects oflonger Is and shorter Ts.…”

Analysis of a trial-spacing effect with relatively long intertrial intervals

“…The present experiments do not distinguish between these two types of accounts. However, it is worth noting that Sunsay (2004) failed to confirm the comparator theory's prediction of an effect of extensive context exposure on performance to the CS when it was administered after conditioning when a short (240-sec) ITI had occurred (see also Holland, 1999). Finally, as we noted earlier, a time-accumulation model (Gallistel & Gibbon, 2000) would predict the role of context exposure only if it assumed that the internal clock that estimates reinforcement rate in the absence of the CS runs only in the context in which conditioning occurs.…”