Selective Attention

Selective attention is mainly concerned with the selection of a limited number of stimuli or objects from among a much larger number of competing stimuli. This happens because our perceptual system has only a limited capacity to receive and process information at any given moment, meaning it can genuinely deal with only a few stimuli at a time. Psychologists have identified a range of factors that determine exactly which of the many available stimuli actually get selected, generally grouped into external factors and internal factors.

External factors relate to the characteristics of the stimuli themselves. With other things held constant, the size, intensity, and motion of a stimulus are important determinants of whether it draws attention -- large, bright, and moving stimuli tend to catch our attention easily, and stimuli that are novel or moderately complex also readily draw our focus. Research indicates that photographs of human beings are more likely to be attended to than photographs of inanimate objects, that rhythmic auditory stimuli are more readily attended to than plain verbal narration, and that sudden, intense stimuli have a particularly strong capacity to capture attention.

Internal factors lie within the individual perceiver, and can be divided into two broad categories: motivational factors and cognitive factors. Motivational factors relate to our biological or social needs -- when we are hungry, we notice even a faint smell of food, and a student sitting an examination is likely to focus more closely on the invigilator's instructions than on the other students in the room. Cognitive factors include things like interest, attitude, and preparatory set: objects or events that seem interesting to us are readily attended to, we also tend to pay quick attention to things we are favourably disposed toward, and a preparatory set generates a mental readiness or predisposition to respond to one particular kind of stimulus rather than to others. …