The modality effect is a term used in experimental psychology to explain the effect of how information is presented has on memory and learning. Research carried out by Sweller et al in 1988 and Moreno and Mayer in 1999 has shown that memory load is reduced when information is presented in an auditory manner rather than a visual one. Specifically, it has been found that there is an improvement in the recall of the final items in a list when the list was spoken rather than read.
Modality of presentation and its effect on learning has been of interest to psychologists for many years. An early review of the relevant literature by McGeoch in 1942 concluded that there is no modality effect. Later studies, however, support the general view that auditorily presented materials are better recalled than visually presented materials when measuring short-term memory. This applies more to the last four or five items on a list with the middle positions seemingly little affected by the modality effect.
One explanation of this phenomenon is the existence of echoic memory which is the auditory sensory register or auditory store retaining a sound input for two or five seconds after it has been uttered or heard. This sensory memory allows the learner to recall the last few items on a list but, because the information has not been processed or studied, long-term recall is often not possible. Long-term memory requires physical changes in the brain which comes about by information processing.
In 1969, Crowder and Morton proposed that human beings have a pre-linguistic auditory store, PAS, which stores speech sounds for up to two seconds. This information is highly available to recall and easily re-circulated but poorly processed. In order for the items in PAS to be recalled at a later date, they first need to be encoded in the brain through methods such as repetition and rehearsal.
Both Sweller et al and Moreno and Mayer contend that when multimedia instruction consists of a text and a picture, there is a high demand placed on the working memory as the learner needs to integrate visual and spatial information. Working memory is another term for short-term memory. Memory load was found to be reduced when the learner had to process auditory information only. According to a working memory model presented by Baddeley (1992), there are two modality-specific slave systems involved in the processing of information. The first is for processing visual and spatial information and the second is for processing acoustic information. When information is presented in both modalities at the same time, then total working memory capacity is increased.