One model of mental representations is the dual- code theoryproposed by Paivio (1969,1971).
This theory suggests that they are separateverbal and non-verbal systems for representing information. In other words,both pictorial and verbal codes are used to represent information in our mindsand these two codes organise information into knowledge that can be acted on,stored and later retrieved for subsequent use (Sternberg & Sternberg, 2012).The types of codes include analog codes that are used to for visual informationby creating mental images of the real word object they are representing. Therefore,analog codes are the near equivalent representation of the physical stimuli we perceivein our environment, such as rivers and trees. Symbolic codes are used to form mentalrepresentations of verbal information e.
g. words. These codes are a form ofknowledge representation that has been chosen arbitrarily to express somethingthat does not perceptually bear resemblance to what is being represented (Stenberg& Stenberg, 2012). The two distinct codes used for mental representation havebeen supported by neurological research by Roland and Fridberg (1985). This isbecause they found that different brain areas were activated when the participantswhere asked to imagine a mnemonic (verbal information) or the route to theirhome from a specific location (visual information). This shows there is adouble dissociation between the two systems, therefore illustrating informationcan be mentally represented through pictorial and verbal codes. However, in contrast the propositional theory proposed byPylyshyn (1973) argues that we do not primarily store mental representations asimages or mere words as suggested in the dual- code theory but that mentalrepresentations are stored generic codes called propositions.
A proposition isa statement or assertion of the relationship between concepts (Johnson, 1998).For example, Clark and Chase suggest that according to the propositional view,both verbal statement and images are mentally represented in terms of theirdeep abstract meanings, and not as specific images and words. The shorthandform known as “predicate calculus” are used to express propositions becausethey intend to show how the underlying meaning of knowledge might berepresented. For example, a bottle under a table would be represented by aformula made of symbols like UNDER(BOTTLE,TABLE).This theory is supported by Weisberg, 1969. This is because they found participantsrecalling words from a previously encountered sentence were more likely toassociate the word given by the experimenter to a word from the same propositionrather than to a word that had a closer position to the given word. Also,Ratcliff and Mckoon, 1978 found that participants were faster at recalling aword that had appeared in a recent sentence when it was immediately precede bya word form the same proposition than when it is preceded by a word from adifferent one.
Therefore, the individuals recalled the underlying relationshipbetween the two words rather than the perceptually and spatial relationshipbetween the words, indicating that mental representations are stored as propositionsrather than pictures or words.