Attention

Around you right now are many sights and sounds: a fan, traffic, people talking. Yet you are reading these words. Attention is the process of selecting some stimuli from many and keeping the mind on them. It involves alertness, concentration and search.

What we attend to is in the focus (centre) of our awareness; other things stay in the fringe, dimly noticed. A sudden loud sound can move something from the fringe into the focus.

Selective attention is choosing a limited number of stimuli from a large number. Two kinds of factors decide what is chosen:

• External factors (features of the stimulus itself): size (a huge billboard), intensity (a bright light, a loud siren), motion (a moving object), and novelty and complexity (something new or unusual).
• Internal factors (inside the person): motives and needs (when you are thirsty, you notice the water cooler in a crowded station), interests, attitudes, and preparatory set (being ready to respond in a certain way, like a sprinter waiting for the start signal).

Three theories of selective attention:

• Filter theory (Broadbent, 1958): many stimuli reach our senses at once, but a selective filter lets only one pass through to higher processing; the rest are blocked.
• Filter-attenuation theory (Treisman, 1962): the stimuli that do not get through are not completely blocked, only weakened (attenuated). Some can still slip through, which is why an important stimulus, such as a parent calling from the next room while you are watching a film, can break into your attention.
• Multimode theory (Johnston and Heinz, 1978): attention works in three stages: first a sensory representation (the shape and features: lines, curves, colours), then a semantic representation (its meaning: 'this is a bus'), and finally both enter consciousness.

Sustained attention (also called vigilance) is the ability to keep attention on something for a long time, as an air-traffic controller must. It is affected by:

• Sensory modality: attention lasts longer for auditory signals than visual ones.
• Clarity: clear, intense stimuli are easier to follow than faint or blurred ones.
• Temporal uncertainty: stimuli that come at regular, predictable intervals are easier to keep track of than ones that come at random times.
• Spatial uncertainty: stimuli that appear in a fixed place are easier to watch than ones that appear in different places. Note: motion catches attention, but a fixed position keeps it.

Divided attention means attending to two things at once. It works for tasks that are highly practised and nearly automatic (an experienced cyclist can chat while riding), but not for new or demanding tasks; texting while driving is dangerous for this reason.

The span of attention is the number of items we can take in at one glance, about 7 plus or minus 2. Some children have attention-deficit hyperactivity disorder (ADHD), with inattention, impulsivity and over-activity; with support and training, most can learn to manage it.