Covariation in conditioned response strength between stimuli trained in compound

Conditioned lick suppression by water-deprived rats was used to elaborate on recent evidence that the attenuated conditioned response elicited by an overshadowed stimulus may be enhanced by extinction of the overshadowing stimulus with which it had been trained in simultaneous compound. Using a modified serial stimulus arrangement in which a light coexisted with the last half of a tone that terminated with footshock, it was found in Experiment 1 that the tone overshadowed the light. Extinction of the tone-shock association resulted in a virtually complete recovery of the response to the overshadowed light. Using this serial overshadowing procedure, the possibility that the strength of a conditioned response to an element trained in compound covaries as a function of the strength of the response to the other element was tested in Experiment 2. Following overshadowing training similar to that of Experiment 1, independent reinforcement of the overshadowed light, that is, associative inflation, was found to have no deleterious effect on the response to the overshadowing tone. This suggests that the effects of postconditioning extinction and inflation of one element do not have symmetrical effects upon responding to the other element. The results of Experiment 2 were replicated in Experiment 3 using a simultaneous compound stimulus as opposed to the serial compound of the previous studies. These results are discussed in terms of various associative and cognitive models of learning and performance.     

Spanning the Academy-Practice Divide with Doctoral Education in Business

The economy has always been a knowledge economy. We accept as a premise of this paper that phenomena such as the explosion of information, information technology, intellectual capital, knowledge workers and firms as knowledge systems are real, while reserving space elsewhere for the critique of such phenomena. To date, doctoral education in business has focused almost exclusively on the needs of future academic staff. One response to the growing demand for a practitioner-oriented doctoral education is the rise of Doctorate of Business and Administration (DBA) programmes. The DBA differs from a Doctor of Philosophy (PhD) because of its increased focus on the application of knowledge, in addition to the development of that knowledge. While PhD research needs to make a significant contribution to theory, DBA research is expected to contribute to both theory and practice. This paper provides a brief history of doctoral education in business. We discuss the choices that have been taken in the design and content of the Massey DBA in relation to the academic/practice divide. An interim report of experiences by both academics and students is provided. The implications for doctoral education in areas that span the research/practice divide are then identified.     

Pavlovian conditioning in multiple contexts: Competition between contexts for comparator status

Water-deprived rats were used to investigate the effects of training a CS in more than one context on conditioned lick suppression. In each experiment, partial reinforcement of the CS was intermingled with unsignaled presentations of the US. In Experiment 1, subjects were either trained in one context alone, trained consecutively in two contexts (such that all training in one context occurred prior to any training in the second context), or trained alternately in two contexts. Following training, the first context, the second context, or neither context was extinguished. Testing of the CS occurred in a third (neutral) context. To the extent that either training context became established as a comparator stimulus for the CS, the comparator hypothesis (Miller & Matzel, 1988) predicts an increase in excitatory responding to the CS following extinction of that context. Subjects trained in a single context exhibited appreciable fear of the CS only when the CS’s training context had been extinguished. Additionally, subjects trained consecutively in the two contexts showed increased fear of the CS following extinction of the second, but not the first training context (i.e., a recency effect). Subjects trained alternately in the two contexts showed no increased fear of the CS as a result of either context alone being extinguished. In Experiment 2, subjects trained alternately in two contexts showed increased fear of the CS only when both training contexts were extinguished, suggesting that both training contexts had become comparator stimuli. These data indicate that multiple training contexts can either compete or act synergistic-ally in modulating responding to a Pavlovian trained CS as a function of the order of training in the different contexts.     

Signaling a change in cue-outcome relations in human associative learning

In three experiments, we assessed the role of signals for changes in the consequences of cues as a potential account of the renewal effect. Experiment 1 showed recovery of responding following extinction when acquisition, extinction, and test phases occurred in different contexts. In addition, extinction treatment in multiple contexts attenuated context-induced response recovery. In Experiment 2, we used presentations of an extraneous stimulus (ES), instead of context shifts, and found that responding recovered from extinction only when the ES was presented both between acquisition and extinction and between extinction and test. In Experiment 3, we used a reversal learning design in which, during training, two cues were first paired with different outcomes, then paired with the alternative outcomes, and finally paired again with the original outcomes. In this experiment, presentation, just prior to testing, of an ES that had previously been presented between the different phases produced an expectation of reversal in the meaning of the cues.     

Latent inhibition of the conditioning context: Further evidence of contextual potentiation of retrieval in the absence of appreciable context-US associations

Previous research in our laboratory has found superior performance when classically conditioned responses are observed in the training context as opposed to outside it, even when direct context-US associations have been minimized by either the choice of conditioning parameters or extinction to the context. The present experiment used latent inhibition of the conditioning context as an alternative method of examining contextual cue effects in the absence of appreciable direct context-US associations. Water-deprived rats received tone-footshock pairings in one of two distinctly different apparatuses, but all were tested in a common apparatus. Animals conditioned in the test enclosure displayed more lick suppression than those conditioned outside the test enclosure. Other animals tested without the tone present also exhibited more suppression if conditioning had occurred in the test context rather than outside it, indicating that direct associations between the conditioning context and shock had been formed. However, when formation of direct associations to the conditioning context was attenuated in additional animals through extensive preexposure to the context prior to conditioning, more suppression to the tone was still seen when conditioning had occurred in the test context rather than outside it. These results add support to the position that the training context augments recall even when direct associations between the context and the US are attenuated. The phenomenon is discussed in terms of facilitated retrieval of nominal CS-US associations, configural retrieval cues, and conditional discriminations.     

Preschool phonological representations and development of reading skills

Individual differences in the quality of phonological representations of kindergarten children may be predictive of Grade 1 phonological awareness and reading development. Three longitudinal studies are presented that attempt to measure variance in the quality of the phonological structures within lexical items using three tasks: non-word repetition, cued word fluency, and a gated auditory word recognition task. Nonword repetition was a consistent predictor of later phonological awareness, even after current phonological awareness and vocabulary knowledge were taken into account. The results of the three studies provide inconclusive support for the theory that individual differences in the quality of phonological representations play an important role in the development of explicit phonological awareness and reading acquisition. An important finding of the third study is that caution needs to be maintained in measuring skills in preschoolers as stability of results can be an issue when interpreting the relations between variables. However, the present studies do confirm that individual differences in vocabulary, nonword repetition, and phonological awareness are important factors in predicting the development of reading related skills.