Page 3 - Sensory, Attentional and Perceptual Processes

Filter-attenuation theory
1. was developed by Triesman (1962) by modifying Broadbent’s theory.
2. This theory proposes that the stimuli not getting access to the selective filter at a given

moment of time are not completely blocked.
3. The filter only attenuates (weakens) their strength.
4. Thus some stimuli manage to escape through the selective filter to reach higher levels
of processing.
5. It is indicated that personally relevant stimuli (e.g., one’s name in a collective dinner)
can be noticed even at a very low level of sound.
6. Such stimuli, even though fairly weak, may also generate response occasionally by
slipping through the selective filter.

Multimode theory
1. was developed by Johnston and Heinz (1978).
2. This theory believes that attention is a flexible system that allows selection of a
stimulus over others at three stages.
3. At stage one the sensory representations (e.g., visual images) of stimuli are
constructed;

4. at stage two the semantic representations (e.g., names of objects) are constructed;
5. at stage three the sensory and semantic representations enter the consciousness.
6. It is also suggested that more processing requires more mental effort.
7. When the messages are selected on the basis of stage one processing (early selection),
less mental effort is required than when the selection is based on stage three
processing (late selection).

SUSTAINED ATTENTION: Sustained attention is concerned with concentration. This

refers to our ability to maintain attention on an object or event for longer durations. It is
also known as “vigilance”. Several factors can facilitate or inhibit an individual’s
performance on tasks of sustained attention.
FACTORS
1. Sensory modality is one of them. Performance is found to be superior when the
stimuli (called signals) are auditory than when they are visual.

2. Clarity of stimuli is another factor. Intense and long lasting stimuli facilitate
sustained attention and result in better performance.
3. Temporal uncertainty is a third factor. When stimuli appear at regular intervals of
time they are attended better than when they appear at irregular intervals.
4. Spatial uncertainty is a fourth factor. Stimuli that appear at a fixed place are readily
attended, whereas those that appear at random locations are difficult to attend.