Models of Visual Attention

Humans have an ability to not attend to all the features of the environment. This offers a functional advantage. There is a focus as to how we direct our attention to specific details.

• An example of a location based model is the Spotlight & Zoom-Lens model
• Alternately there is an Object Based model

Spotlight of Visual attention

• This says that everything within a small region of visual field can be seen clearly. It is more difficult to see anything that doesn't fall within that beam.
• The information that is within the spotlight is processed more clearly than anything outside.
• Precueing Procedure - Posner et al. (1980). In this experiment, participants had to identify when a light appears. In the centre of the row, a precue was given to direct attention to the right or left. When a valid cue was given, there were faster reaction times than when an invalid cue was given. This supports the model of location based attention as the individuals spotlight of visual attention is diverted by the precue, making the light more easy to identify when it is within that visual field, or, more difficult to identify if it is outside the spotlight.

Zoom Lens Model

• This is an adaptation of the spotlight model.
• It says that attention is directed to a particular region of visual field.
• The area however ca be increased or decreased depending on the requirements.
• LaBerge (1983): In this experiment, participants were presented with 5 letter words. There were 2 conditions. In one condition, a probe would appear in place of a letter, in the other condition however, the probe would appear in place of a word. The results showed that the reaction time was faster when the participants had a narrower attentional beam, ie. in the first condition.
• There is less evidence for the zoom-lens than for the spotlight model, as we can still process unattended visual stimuli.

Visual search

• This is when something specific is sought out of a range of items.
• It can be lead by top-down processing eg shopping using a list (personal objectives) or by bottom-up processing eg being lead by visual salience, being distracted by an attractive object.
• Experimental studies relating to this, ask participants to identify specific targets within a visual display. Their success is dependent upon the distinguishing features of the target, and how many conflicting or distracting items there are.

The Flanker Task

• This is an example of an experiment testing visual search
• The participant is presented with a number of visual displays and must identify a target shape.
• Distractors are present to divert attention. These can be either compatible, (where the distractor is the same shape as the target), or competing (where the distractor is a different shape to the target)
• It takes people longer to identify the target when there are competing distractors compared to compatible distractors. This indicates that the distractor is processed even though the participants are told to ignore it.
• The Flanker Test can be carried out with either a high or low cognitive load. A low load has just 1 target and distractor, while a high load has many distractors.
• High and low cognitive loads have similar reaction times. This is because, though the high load is more complex, it has all of the attention focussed on it.