Similarities between Pavlovian conditioning in nonhumans and causal judgment by humans suggest that similar processes operate in these situations. Notably absent among the similarities is backward blocking (i.e., retrospective devaluation of a signal due to increased valuation of another signal that was present during training), which has been observed in causal judgment by humans but not in Pavlovian responding by animals. The authors used rats to determine if this difference arises from the target cue being biologically significant in the Pavlovian case but not in causal judgment. They used a sensory preconditioning procedure in Experiments 1 and 2, in which the target cue retained low biological significance during the treatment, and obtained backward blocking. The authors found in Experiment 3 that forward blocking also requires the target cue to be of low biological significance. Thus, low biological significance is a necessary condition for a stimulus to be vulnerable to blocking. In recent years, numerous researchers have remarked on the similarity of the conditions that encourage the acquisition of causal relationships in humans and those that foster

“that process which manifests itself by adaptive changes in individual behaviour as a result of experience. ” Thorpe (1963) Manning and Dawkins (1992), and their more recent edition, both state that the old approach to learning has “been replaced by a much more biologically based approach.... learning is now seen as a way in which animals attempt to identify key aspects of a fluctuating environment: to detect its regularities and ignore the distracting ‘noise ’ which is not important for them.” My aim in these lectures is to discuss how animals pick out the relevant detail and much of the material is drawn from a classic book by Dickinson (1980) recommended by Manning and Dawkins. The ideas in the book are important but it is a hard read. I have tried to extract the best bits and place them in an intelligible framework. That means I have had to skip many other aspects of learning and memory but these are covered by Manning and Dawkins (1992) and in other introductory texts. Most of these commend the modern approach but make no attempt to explain it. An exception is Pearce (1997, Chapter 3) which gives a good account of theoretial developments since

In Stage 1 of 4 experiments in which rats completed a water-maze blocking procedure, experimental groups were trained to use a predictive beacon (hanging above, connected to, or displaced from the platform) to find a submerged escape platform in the presence of predictive or irrelevant background cues and in the presence or absence of irrelevant landmarks. In Stage 2, a fixed beacon, landmarks, and background cues all predicted the platform location. A Room Test (landmarks and background cues only) showed that Stage 1 training with a fixed hanging beacon or the moving displaced beacon facilitated Stage 2 learning of predictive room cues for experimental relative to control subjects. In contrast, Stage 1 training with a moving pole beacon interfered with Stage 2 learning about predictive room cues relative to controls, whereas training with a fixed pole or moving hanging beacon had no effect. We conclude that multiple spatial learning processes influence locating an escape platform in the water maze.