A lesson in social psychology: social influence

Key terms

Social facilitation – the tendency for people to perform better on tasks in the presence of others than when alone (because the performer produces little arousal, which, coupled with the audience’s arousal, reaches the optimum peak of the Yerkes-Dodson curve)

Social inhibition – the tendency for a person’s performance to decline in the presence of others than when alone (because the performance requires too much arousal)

(Physiological) arousal – how energised, alert and ready for action a person is

Dominant response – a well learned and thoroughly practiced ‘automatic’ behaviour which is more likely to occur when a person is highly aroused in a stressful situation

The link between these terms, summarised:


The Yerkes-Dodson curve


The bell shaped curve shows that as arousal increases, performance rises to an optimum point before declining with too-high levels of arousal.

Concept applied to an example: A group of 3 students provides enough arousal to reach the optimum and thus achieves an excellent standard of work together. With the addition of 2 more students performance begins to decline as arousal is too high, resulting in disruptive behaviour and a lack of work.

Studies that support these theories

Triplett (1897) – 40 children aged 7-18 had to wind 16m of string around a fishing reel as fast as possible. They did this alone and with a co-actor, and were timed. It was found that the majority of participants were 2-3 seconds quicker when performing with a co-actor than when performing alone. 

Explanation: Winding string around a fishing reel is an easy task so the dominant response is to do this well. Little arousal is required so with the presence of another person(‘s arousal), the solo performer reaches a peak with the peak arousal levels.

Zajonc et al (1969) – Female cockroaches were timed on how long it took them to run in a straight line from a bright light when enclosed in a perspex box. They did this when alone and again with an audience of 4 other cockroaches. This procedure was then repeated but the task was made more complex by adding a corner that the cockroaches has to turn when escaping the light. The results found that cockroaches were 8 seconds faster running in a straight line in the presence of an audience than when alone. However, they were 20 seconds faster alone when they were required to run around the corner.

Explanation: Running in a straight line was the dominant response and so was aided with the presence of an audience. The added complexity of the corner raised the arousal levels and the cockroaches’ dominant response was to make more mistakes in this scenario, thus taking a longer time.

Theories of arousal

Mere presence – the presence of others increases arousal because as animals we must be alert to the possibility that they will do something which we must respond to – an innate, biological tendency.

Evaluation apprehension – the presence of others makes us worried that we will be judged or face possible embarrassment. Anxiety has the effect of increasing arousal levels.

Distraction-conflict – the presence of others distracts us, creating a conflict as our attention continually shifts between paying attention to the audience or other source of distraction and paying attention to the task. This conflict thus raises arousal levels.

Evidence for theories of arousal

Baron (1986) – Participants has very easy tasks to complete. One group of participants completed these in front of an audience and the other completed them in front of a flashing light (which acted as a distraction). Baron found no difference in the performance of the two groups.

Paulus and Murdoch (1971) – Students has to complete easy and difficult word-recognition tasks with and without an audience. One group of participants were told that the audience consisted of psychology professors and the other group were not. When measuring performance levels during the difficult task it was found that the group who were told of the psychology professors performed worse than the other group, who were not affected.

Source: Billingham, M. et al (2008) AQA Psychology B AS: Student’s Book, Nelson Thornes: Cheltenham



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