Ontogeny of persistence: Immediate extinction effects in preweanling and weanling rats

Abstract

In Experiment I rats were trained for 2% days under partial (PRF) or continuous reinforcement (CRF) conditions starting at 18, 22,28, or 36 days of age and were then subjected to immediate extinction. At all ages there was a strong partial reinforcement extinction effect (PREE), and absolute size of PREE was greatest in the youngest rats. Rate of extinction increased as a function of age following both CRF and PRF. In Experiment II the youngest and oldest age groups of Experiment I were run under the two reward conditions of Experiment I and in a third condition, PRF with number of rewards rather than trials equated to CRF (PRF-R). The PRF-R and PRF groups were not different in extinction, and both were more persistent than CRF. The youngest rats were again more persistent than the oldest, particularly after PRF training. In Experiment III it was shown that the well-known paradoxical effect, greater reward in CRF acquisition leads to faster extinction, operates in our youngest and oldest animals, but is more pronounced in the oldest. The results are discussed in terms of whether they require different explanations than those often applied to extinction data from adult rats.We seem to know much more about the ontogeny of aversive (fear) conditioning in rats than about appetitive learning, perhaps because it seems easier to equate motivational factors at different ages in aversive than in appetitive learning (Campbell, 1967). However, we do have a little information on how level of maturity in rats affects learning in appetitive situations. Weanling rats are reported to be inferior to adults in learning a barpress response for food reward and in forming a lightdark discrimination (Campbell, Jaynes, & Misanin, 1968). Similarly, juvenile rats (less than 50 days of age) do less well on a spatial discrimination than adults (Bronstein & Spear, 1972). The younger rats in the studies of Campbell and his colleagues also show poorer retention of both a learned barpress and light-dark discrimination (Campbell et al., 1968), unless there are periodic reexposures of the rats to the experimental task over the retention interval (Campbell & Jaynes, 1969).While these experiments tell us something about the ontogeny of appetitive learning, they fall short of being decisive in several respects. First, the number of ages investigated is small over the range of ages investigated. This makes it difficult to determine the age at which an adult pattern first appears, and says little about the abruptness of the transition. A second related point is that, when traimng sessions are conducted over an extended period of time, it is difficult to separate changes in performance related to developmental factors from changes resulting from amount or duration of training. Finally, experimental treatment of the youngest subjects in these studies on appetitive learning usually begins in the fourth postnatal week or later,

Précis ofFrustration Theory: An Analysis of Dispositional Learning and Memory

“…In chapter 7, I examine the ontogeny ofa number of these behavioral effects. Here are some examples: At II days of age, rat pups can learn to discriminate the presence or absence of reward on the basis of a singlealternating pattern~approaching a goalbox rapidly on odd-numbered, rewarded trials and greatly suppressing Successive acquisition and extinction (Amsel, Burdette, & Letz, 1976) ,,; I0 days Single patterned alternation (PA) (Stanton, Dailey, & Amsel, 1980) ,,;11 days Partial reinforcement extinction (PREE) (Chen & Amsel, 1980a, 1980cLetz, Burdette, Gregg, Kittrell, & Amsel, 1978) 12-14 days Variable magnitude of reinforcement extinction (VMREE) 16-18 days Partial delay of reinforcement extinction (PDREE) 16-18 days Partial reinforcement acquisition (PRAE) (Chen, Gross, Stanton, & Amsel, 1980) 18-20 days Magnitude of reinforcement extinction (MREE) (Burdette, Brake, Chen, & Amsel, 1976;Chen, Gross, & Amse1, 1981) 20-21 days Successive negative contrast (SNC) 25-26 days Slow responding (DNC) (Chen, Gross, Stanton, & Amsel, 1981) ,,;63 days From "Developmental Psychobiology and Behavior Theory: Reciprocating Influences," by A. Amsel, 1986, Canadian Journal ofPsychology, 40, p. 315.…”

Dissociation of patterned alternation learning and the partial reinforcement extinction effect in preweanling rats

“…Beyond this general trend, however, we have found that the PREE appears much earlier in ontogeny than do other paradoxical effects. The PREE first appears at 12-14 days (Chen & Amsel, 1980;Letz, Burdette, Gregg, Kittrell, & Amsel, 1978), whereas the MREE fails to appears clearly until about 21 days (Burdette, Brake, Chen, & Amsel, 1976;Chen, Gross, & Amsel, 1981;; SNC first appears at 25-26 days (Chen et al, 1981;; and there is no evidence of the OEEprior to 25-26 days . The sequence of appearance of these extinction effects remains to be explained by theories that attribute these effects to a common set of learning mechanisms.…”

Periadolescence: Age‐dependent behavior and psychopharmacological responsivity in rats

“…Animals trained between 33 to 45 days of age are less persistent than younger or older animals. Thus, periadolescents showed greater resistence to extinction after intermittent than after continuous reinforcement, but the effect was significantly less robust than in younger and older animals (Amsel & Chen, 1976, Experiment 3;Burdette et al, 1976, Experiment 1). An even more striking finding was that rats intermittently rewarded for running at 31-33 days of age and given extinction trials 10 days later, at 44 and 45 days of age, displayed no persistence during extinction whatsoever (Brake et al, 1980; see Fig.…”

“…A series of experiments designed to investigate the ontogeny of instrumental learning and behavioral persistence illustrates this point. These experiments Brake et al, 1980;Burdette, Brake, Chen, & Amsel, 1976) revealed that 17-, 23-, 27-, 33-, 4 5 , and 56-day-old Sprague-Dawley rats (of both sexes), like adults, are capable of learning to run down an alley for a food reward, even though a reward is presented on only 112 of the successfully completed trials. Also, like animals at other ages, periadolescent rats that receive rewards intermittently during acquisition of the response tend to persist more in their efforts to secure rewards during extinction (when no reward is given) than animals that had been consistently rewarded in acquisition.…”