Autoshaping [autoshaping classical conditioning used with pigeons which results in pecking at an illuminated response key that has been regularly presented before the delivery of food, even though the delivery of the food does not depend on the pecking behaviour]
A hungry pigeon is presented with grain (US) preceded by the illumination for ten seconds of a small light (CS) fixed to the wall of the cage. After 50 to 100 trials, the bird develops the CR of pecking at the light prior to food delivery. It is as if the bird is predisposed to respond to the light even though the pecking does not influence whether or not it receives the grain.
Flavour aversion learning [flavour aversion learning classical conditioning procedure in which animals are allowed to consume a substance with a novel flavour and are then given some treatment that induces nausea, resulting in the flavour being subsequently rejected]
Rats are given a novel flavour (e.g. saccharin is added to their drinking water) as the CS. This is followed by a procedure, such as the injection of a mild poison into their body, that makes them feel sick (the US). When it is subsequently made available, the rats will no longer consume the saccharin-sweetened water; they have developed an aversion (CR) to that flavour. This is clearly a very varied set of phenomena, but what they all have in common is the presentation of two stimuli, one contingent on the other. And, despite the fact that there is nothing in these training procedures that actually requires a change in behaviour, in every case the animal’s behaviour changes as a result of its experience. In the autoshaping case, for instance, the experimenter simply ensures that the light reliably accompanies food. There is no need for the pigeon to respond to the light in any way, since food is delivered regardless of the bird’s behaviour. So why does behaviour change? Why are conditioned responses acquired This puzzle must be dealt with by more detailed theoretical analysis.
When a dog trained by Pavlov’s procedure sees the light (CS), certain neural mechanisms are activated. Without specifying what these mechanisms are, we can refer to this pattern of activation as constituting a representation of the CS. This is often referred to as the CS ‘centre’, implying that it is localized in a specific part of the brain, although this might not necessarily be the case (for the purposes of our current behavioural analysis, this does not matter too much). Eating food (the US) will also have its own pattern of proposed neural activation, constituting the US representation or ‘centre’. One consequence of the Pavlovian conditioning procedure is that these two centres will be activated concurrently. Pavlov suggested that concurrent activation results in a connection between the two centres, which allows activation in one to be transmitted to the other. So, after Pavlovian learning has taken place, presentation of the CS becomes able to produce activity in the US centre, even when the food has not yet been presented. This theory therefore explains classical conditioning in terms of the formation of a stimulus–stimulus association between the CS centre and the US centre. (Given this framework, the fact that the presentation of the US provokes an obvious response is not strictly relevant to the learning process.)
A hungry pigeon is presented with grain (US) preceded by the illumination for ten seconds of a small light (CS) fixed to the wall of the cage. After 50 to 100 trials, the bird develops the CR of pecking at the light prior to food delivery. It is as if the bird is predisposed to respond to the light even though the pecking does not influence whether or not it receives the grain.
Flavour aversion learning [flavour aversion learning classical conditioning procedure in which animals are allowed to consume a substance with a novel flavour and are then given some treatment that induces nausea, resulting in the flavour being subsequently rejected]
Rats are given a novel flavour (e.g. saccharin is added to their drinking water) as the CS. This is followed by a procedure, such as the injection of a mild poison into their body, that makes them feel sick (the US). When it is subsequently made available, the rats will no longer consume the saccharin-sweetened water; they have developed an aversion (CR) to that flavour. This is clearly a very varied set of phenomena, but what they all have in common is the presentation of two stimuli, one contingent on the other. And, despite the fact that there is nothing in these training procedures that actually requires a change in behaviour, in every case the animal’s behaviour changes as a result of its experience. In the autoshaping case, for instance, the experimenter simply ensures that the light reliably accompanies food. There is no need for the pigeon to respond to the light in any way, since food is delivered regardless of the bird’s behaviour. So why does behaviour change? Why are conditioned responses acquired This puzzle must be dealt with by more detailed theoretical analysis.
When a dog trained by Pavlov’s procedure sees the light (CS), certain neural mechanisms are activated. Without specifying what these mechanisms are, we can refer to this pattern of activation as constituting a representation of the CS. This is often referred to as the CS ‘centre’, implying that it is localized in a specific part of the brain, although this might not necessarily be the case (for the purposes of our current behavioural analysis, this does not matter too much). Eating food (the US) will also have its own pattern of proposed neural activation, constituting the US representation or ‘centre’. One consequence of the Pavlovian conditioning procedure is that these two centres will be activated concurrently. Pavlov suggested that concurrent activation results in a connection between the two centres, which allows activation in one to be transmitted to the other. So, after Pavlovian learning has taken place, presentation of the CS becomes able to produce activity in the US centre, even when the food has not yet been presented. This theory therefore explains classical conditioning in terms of the formation of a stimulus–stimulus association between the CS centre and the US centre. (Given this framework, the fact that the presentation of the US provokes an obvious response is not strictly relevant to the learning process.)
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