Explanation: Piliavin et al. developed a model to explain their results called the Arousal: Cost – Reward Model.They argue that firstly, observation of an emergency situation creates an emotional arousal in bystanders. This arousal may be perceived as fear, disgust or sympathy, depending on aspects of the situation. According to Piliavin et al. the results of their fiield experiment can be explained using their Arousal: Cost – Reward Model. For example:The drunk is helped less often because the perceived cost is greater - helping a drunk is likely to cause disgust, embarrassment or harm. The cost of not helping is less because nobody will blame another for not helping a drunk because he is perceived as partly responsible for his own victimisation. Women help less often than men because the cost to them in terms of effort and danger is greater and, since it may not be seen as a woman’s role to offer assistance under these circumstances, the cost of not helping is less. Diffusion of responsibility is not found in the cane-carrying situation because the cost of not helping is high and the cost of helping is low. As time without help increases, so does the arousal level of the bystanders. A late model is not copied because people have already chosen an alternative way of reducing arousal; they leave the area or engage in conversation with others in order to justify their lack of help.