Divided attention refers to the ability to divide ones attention between two or more tasks. The focused attention models explain how all our inputs are focused on one task at any one time, however it is clear from looking at everyday life that we are able to divide our attention, successfully being able to complete more than one task at the same time. There are two main explanations of divided attention, one is the modular theories and the one I will be focusing on; the capacity model by Kanheman.
Kanheman (1973) put forward the capacity/resource allocation model of attention. This is one of the best known models and suggests that humans have a limited amount of processing capacity and whether two or more tasks can be performed together successfully depends on how much demand they make on this limited capacity processor. This idea of a limited capacity is very probable and has been clear to be the case from earlier research carried out on divided attention.
As well as the capacity, external factors such as heat, noise, anxiety and lack of sleep may also affect performance on tasks related to attention (Revelle). Findings such as these do support the capacity models of attention.
According to Kanheman different tasks require a different amount of processing. So, easy tasks will require little processing capacity and leave plenty available for carrying out another task at the same time, whereas more difficult tasks require a lot more processing capacity, so maybe can only be carried simultaneously with another task which doesn't require so much. The amount of capacity that a task requires depends on a number of things such as its difficulty and past experience of the task. If past experience of the task is increased, and practise is undertaken the same process which may once have required a lot of processing soon becomes automatic, meaning that it can be carried out with less processing. Underwood can account for this in his findings, as he carried out an attention tasks on participants with one group having practised the task, so the skilled participants and another group who had not practiced the task. He found that the experienced shadowers recalled a great deal more from the unattended channel than inexperienced ones.
In addition arousal is seen as very important in determining how much capacity is available. When one is alert and aroused, it has been found that more resources are available meaning that attention can be divided between two tasks, however when we become tired, less resource availability makes the capacity needed to complete a simple task more, making it less likely that we can divide our attention.
Kanheman believes that the central processor allocation policy controls the whole attention system by flexibly allocating attentional resources to various tasks. The central processor has a limited pool of attention resources. Kanheman calls the process of determining how much capacity is available "effort" and this...