This essay will look at the different variables and stimuli that are involved in respondent conditioning and how they can affect the effectiveness of respondent conditioning. Watson (1903) developed the law of exercise, which proposed that an association between a stimulus and a response could be forged simply by repeating the two together often enough. This has now become known as classical or respondent conditioning. Pavlov (1927) further defined respondent conditioning. Pavlov also believed that learned associations were strengthened by repetition of association between stimulus and response.

In pavlovian terminology the pairing of an unconditioned stimulus (US) with a conditioned stimulus (CS) repeatedly, would result in a learned behaviour. Pavlov used this theory and experimented on dogs, conditioning them to salivate to the tone of a bell. Pavlov paired the CS of a bell to the US of food, which stimulated the unconditioned response (UR) of salivation. Through enough pairings the dogs learned to associate the CS with the UR, which then became a conditioned response (CR) of salivation to a bell tone.

The most prominent variable in respondent conditioning is the temporal relation between the CS and the US. There are four main temporal relations. The first is simultaneous conditioning. This form of conditioning presents the CS and US at the same time; this may seem the most effective way of conditioning behaviour. However researchers have found it to be a weak procedure for learning behaviour (Bitterman, 1964). Simultaneous conditioning is more effective in real life than in a laboratory experiment.

Simultaneous conditioning can occur with the development of phobias, the sound of a dentists drill accompanied simultaneously by the unpleasant sensation of the drill hitting the tooth elicits a fear response, subsequently going to the dentist will elicit the same fear response. Trace conditioning introduces a gap between the CS and US. The US is presented after the CS has disappeared. This form of conditioning can reduce the degree of conditioned responding that may develop. Moore & Gormezano (1961) looked at the conditioning of human eye blinking conditioning.

Participants were presented with a 500msec interval between the CS disappearing and the US appearing. Moore & Gormezano found that conditioning increased quickly, and after 20 trials at an 80 percent probability of the conditioned response occurring. McAllister (1953) looked at the time between the CS and US. McAllister’s results showed that an 80 percent probability occurred of the conditioned response occurring with an interval of 500msec or less, the percentage decreased the longer the interval was, falling to a 40 percent probability of the conditioned response occurring after 2500msec.

Trace conditioning can, like simultaneous conditioning can be effective outside a laboratory setting, with longer interval occurring. The pairing of lightning followed by thunder can elicit a conditioned response from individuals although the interval between the two can vary from instantly to several seconds. Backward conditioning consists of presenting the US before the CS. This has been researched and seen as the least effective form of respondent conditioning. Pavlov (1927) exposed dogs to an odour of vanilla after administering a mild acid, placed in the dogs mouth (which elicited the US of salivation).

The two stimuli’s were paired a total of 427 times without conditioning occurring. However backward conditioning has shown some effectiveness, however this research is limited (Keith-Lucas & Guttman, 1975). Backward condition can be seen outside the laboratory setting. The US of an individual receiving pain when sitting down, followed by the visual image of the offending object being found. In delayed conditioning the CS and US overlap. The US is presented before the CS has disappeared.

This has been seen as the most effective form of respondent conditioning by many researchers. Kamin (1965) compared fear conditioning in rats using a conditioned suppression procedure. Kamin compared delayed conditioning with trace conditioning. One group received a delayed conditioning procedure in which a tone ended with a shock, without any interval between the CS and US. The second group received a tone and then an interval of 0. 5 sec before receiving a shock. The results showed a lower conditioned suppression in the trace-conditioned group.

Kamin’s results indicate that for a higher rate of respondent conditioning delay conditioning is the most effective within a laboratory setting. The contingency of respondent conditioning refers to the dependency between two stimuli, the CS and US. The contingency between the two stimuli refers to the predictability that the CR will occur with the presentation of only one stimulus. This can be defined in two probabilities. The first is that the US will occur when the CS has been presented, the second is that the US will occur when the CS has not been presented.

Rescorla (1968) subjected rats to a tone followed by a shock, all the rats received equal amounts of CS’s and US’s pairings. Rescorla in additional trials let the US sometimes appear alone. One group received a shock in the absence of the CS 10 percent of the time, a second group received a shock 20 percent of the time and a third group received a shock 40 percent of the time. The results showed that learning depended on the amount on which the CS predicted a shock. The third group, where a shock occurred 40 percent of the time without the CS showed little conditioning.

The contiguity of respondent conditioning refers to that of the interval between the CS and the US. In trace conditioning the contiguity refers to the interval between the end of CS and the presentation of the US. In delayed conditioning, where the CS and US overlap, the contiguity is the interval that starts at the presentation of the CS and ends with the start of the presentation of the US. It has been found that the more contiguous the CS and US the quicker a CR will occur (Mackintosh, 1974).

The interval for the best conditioning effects varies depending upon the CR of the conditioning that is required. Kimble (1947) studied the effect of time between the presentation of a CS and US, using conditions between a 1/10 of a second and 4/10 of a second. It was found that the shorter the interval the less effective conditioning was. However some researchers have found that with studies of taste aversion it is possible to achieve highly effective results with intervals of several hours (Revusky & Garcia, 1970). The contiguity of the CS and US cannot be dismissed.

Although the shorter the interval the more ideal, the optimum interval will vary upon the situation it is being tested in and can depend upon several variables. Other variables that can affect conditioning are that of compound stimuli, overshadowing, blocking, biological effects and intensity. A compound stimulus is a CS that contains two or more stimuli, presented simultaneously. Pavlov (1927) simultaneously presented cold and tactile stimulation to dogs followed by a US. Pavlov tested the tactile and cold stimulus by themselves and the compound stimulus.

The results showed that conditioning occurred with both the tactile and compound stimulus but the cold stimulus alone was found to be ineffective in conditioning. This leads to overshadowing of one stimulus because it does not affect the CR in respondent conditioning. Blocking can be an occurrence of prior history of a CS. Kamin (1969) performed an addition to his 1965 experiment where rats had been exposed to a tone which was then followed by a shock. In addition to this Kamin used the rats and exposed them to a light aswell as a tone, preceding a shock.

Kamin then tested the rats using only the light as a CS; it was found that no conditioning occurred because of the rat’s prior conditioning to the tone, which blocked the conditioning of the light to the shock. Garcia & Koelling (1966) found that rats could learn the ability to associate taste with illness but not with shock and they could learn that noise and sounds associate with shock but not with illness. Garcia & Koelling explained this as a biological constraint because animals and humans biologically associate illness with taste outside a laboratory setting.

The intensity of a CS can affect the level of conditioning that occurs. Spence (1953) studied blinking conditioning with a puff of air being exerted at either 0. 25psi or 5psi. Spence found that fewer responses were made at the lower intensity condition than at a higher intensity. When all of the variables are considered the statement that the variables involved in respondent conditioning are equally effective with all stimuli and with various experimental preparations cannot be considered accurate because respondent conditioning has shown varying levels of effectiveness with different variables and stimuli.