Limited Channel Capacity Research Articles

Where is capacity limited? A survey and a model

A model is presented for the limitations of processing information by the human operator which proposes that he acts not as a limited capacity channel with fixed capacity, but as a limited capacity processor. The total capacity of the brain can be allocated to the separate aspects of the tasks, such as reception, recording, emission, storing, etc. Hence from moment to moment the size of the ‘channel’ in the Shannon sense will appear to vary. In particular parallel processing is possible where the total capacity is not exceeded, and where there is high compatibility. Experimental evidence in support of the model is presented.

Temporal confusions and limited capacity processors

Theories of limited channel capacity should have some implications on the temporal properties of information processing. Little experimental evidence on this topic is available. Four types of observations are mentioned: 1. 1. The perception of a sequence of single auditory notes when the notes are drawn from two different samples of frequencies. 2. 2. The perception of very fast presented visual items. 3. 3. The perception of very fast presented auditory items, some items being presented twice in succession. 4. 4. The reversal error in short term memory experiments. Results of some informal investigations are presented, which demonstrate that resolution of time relations among stimuli depends not simply on temporal factors, but also on stimulus-properties.

Rate of presentation and the acoustic similarity effect in short-term memory

Ss attempted to recall sequences of six consonants drawn from either an acoustically similar set (B C D G P Q T V), or from a relatively dissimilar set (H K M P R S W Y). Letters were presented visually at a rate of 60 or 120 letters per min. Performance was impaired by acoustic similarity (p<.001) but there was no effect of rate of presentation and no interaction between rate and similarity. This does not support a limited channel capacity interpretation of the acoustic similarity effect.