Mental representations are used bythe mind to represent entities that belong in our external reality includingwords, objects and knowledge; they are symbolic and hypothetical and are vitalto our perception of the world around us (Sternberg and Sternberg 2011).Several different theories have been proposed on how the brain uses mentalrepresentations for understanding the world; for example, Dual-Code Theory(Paivio 1969) focuses on the use of two codes (pictorial and verbal) and thesecodes represent information from the environment in our minds. This informationis known as mental imagery and is used to visualise objects which are notcurrently in our direct view (Kosslyn & Rabin 1999 cited Sternberg andSternberg 2011 pg 276).
This theory is different from the Propositional Theory (Pylyshyn1973) as this theory states that our mental representations are more likely tosignify the form of a proposition, i.e. they represent the meaning underlying arelationship between two perceptions so that our mental representations havedeeper meaning rather than being just an image. The third theory is the conceptof Mental Models (Johnson-Laird 1983) and this offers a middle ground betweenDual-Code Theory and the Propositional Theory as it states that we have aworking model for certain analogies in the real world that are neither visualor deeper representations, this working model can be used by individuals tocomprehend and describe their experiences. These different theories of mentalrepresentations will be compared throughout the essay by drawing on thesimilarities and differences between them. The most notable differencesbetween these three theories comes from the principles of the Dual-Code Theoryand the Propositional Theory as these have completely contradictory views onmental representations. The Dual-Code Theory which was suggested by Paivio(1969) states we use verbal and pictorial codes to represent information thatappears in our environment; these codes sort information so that it can be usedto influence our behaviour, it can be stored or retrieved at a later time. Forpictorial codes we use mental images and these mental images are analogous tothe real-life stimuli that we see ourselves and for words we use a symboliccode which is subjectively chosen to replace the perceptually representedobject.
This is very different from the ideals of the Propositional Theorywhich suggests that we do not store our mental representations as words andimages, but in fact, store them as propositions, which is the meaningunderlying a particular relationship among concepts. According to this theoryour perceptions of images and words are stored as their deep meanings and whenwe wish to retrieve the information a proposition between the relationship oftwo objects is retrieved. Mental Models (Johnson-Laird 1983)has both similarities and differences with each of these theories; it issimilar to the Dual- Code theory due to the fact it says we have structuralanalogies of the real world so that our representations are the same as what wesee in real life. This means both theories agree that in our mind we havesimilar symbols to what appear in our environment.
It is also similar to thePropositional Theory as they both agree that a person’s knowledge of the thingsthey are perceiving is important to how they store the mental representation;for mental models can be incorrect (Modell et al 2000) and this demonstrateshow each person’s knowledge can affect the representation. However, the MentalModels Theory also differs from the Dual-Code Theory as the working models candiffer person-to-person depending on the individuals’ understood concepts abouttheir experiences whereas dual-code theory would suggest it shouldn’t change asmental representations are just the same as we see them in real life. Furthermore, Mental Models also differs from thepropositional theory as Mental Models still acknowledges the fact that externalstimuli are represented internally whereas Propositional Theory is completelynon-analogous.There are few similarities sharedbetween the Dual-Code Theory and the Propositional Theory, however, they both share the fact that they havestudies to support and refute them. Paivio (1969) supports his Dual-Code Theorywith a study which portrays the fact that pictorial information and verbalinformation is processed differently. Inthis study participants where shown a sequence of words and then a sequence ofpictures rapidly; they were then asked to recall them sequentially or randomly.It was found that for words the participants would recall them faster if themrecalled them in the same order given yet for words they recalled them fasterwhen they recalled them in any order. These results suggest two differentsystems for recalling words and pictures thus supporting Dual-Code Theory.
However, this evidence did not unchallenged;Chambers and Reisberg (1985) used figures which were ambiguous to determinewhether our mental images were in fact analogical to our perceptions of objectsin reality. When presented with the ambiguous images participants had difficultyinterpreting what the alternative image was suggesting they needed the physicalobject to guess the alternative interpretation. This evidence suggests that wedon’t use mental images to represent objects in external reality and that infact propositional codes are used rather than analogical ones. Evidence for the PropositionalTheory comes from Reed (1974) whereby participants in his study were unable todetermine whether component shapes (e.
g Parallelograms) fitted into a wholegiven figure such as the star of David suggesting they could not use mentalimages. Reed (1974) took this as meaning that a propositional code was usedwhere they had taken the deeper meaning of the star (E.g.
its relationship withreligion) rather than an analogical one. However, again, further studies haverefuted the use of a propositional code and suggested the use of MentalImagery. In a study, participants had to combine two separate images to form anew image in their minds, the new image differed from the sum of the two distinctimages portraying how we can use Mental Images in our mind (Finke et al 1989).This study also suggests that propositional codes are unlikely to overrideimaginal ones when the participants are presented with an image to berepresented. On the other hand, Dual-Code Theorydiffers from both Mental Models and Propositional Theory due to the fact it hasbrain scans to support the use of mental imagery making it more valid as acause and effect relationship is more likely to be the case; due to the fact MentalModels and Propositional Theory focus on ideas which are hypothetical it makesit more difficult for us to prove them making them less reliable. Evidence fromfMRI scans strongly supports the idea for mental images being used in mentalrepresentations. Ganis et al (2004) conducted astudy whereby participants either had to imagine common objects or saw drawingsof them.
The results demonstrated that both visual imagery and visualperception used the same neural areas including the frontal gyrus in thefrontal lobe and the left angular gyrus and the supramarginal gyrus in theparietal lobe. In these areas there was a complete overlap of brain activationfor both mental imagery and the actual perception of objects stronglysupporting the idea of the use of mental imagery in the Dual-Code Theory.Further evidence for the brain using mental imagery comes from looking at brainpatterns during sleep. It has been found that our visual experience while weare asleep shares the same brain activity patterns as if we were seeing stimuliin real life again suggesting that visual codes are in fact analogous of ouractual perceptions (Horikawa et al 2013). The Propositional Theory and MentalModels lacks this kind of evidence due to its ambiguity and therefore differsfrom the isomorphic nature of Dual-Code Theory. Comparisons between Mental Modelsand Propositional theory can be observed as a result of their capability toexplain findings which cannot be explained by the Dual-Code Theory; this isbecause they don’t fully focus on visual imagery as the use for mentalrepresentations. Kerr (1983) studied patients who had been born blind and askedthem to imagine various objects.
His results showed that the blind participantswere always slower then sighted participants at answering questions about theobjects. However, the blind participants showed faster reactions when having toscan shorter distances than when scanning longer distances and when answeringquestions about larger objects than smaller ones. This reflects that not allmental representations can be in fact analogues of the objects we see thereforesuggesting another way in which our mind uses mental representations. Thiscould either be a deeper meaning behind mental representations whereby we usepropositions to understand knowledge in the external reality or that we usemental models from the information we have gathered in our environment. However,in this case the use of mental images cannot be the explanation due to theparticipants being born blind. Finally, Dual code theory differsfrom Propositional Theory and mental models as it focuses on the fact thatimagery and words are processed different in the brain and are representeddifferently in the mind whereas Propositional Theory and Mental Models don’t.According to Paivio (1969) mental images correspond with the objects that theyare representing, i.
e. they are the same as the physical stimulus we see.However, our mental representations for words are represented differently asthey are represented as a symbolic code. This code is a representation ofknowledge which has been chosen arbitrarily to stand for something that is notperceptually resembled.
This is supported by a study where participants had toanswer questions about images and words of pairs of animals and objects. Therewere differences in how fast the participants could answer the questionsrelating to the size of the object and animals depending on whether it waswritten or there was in image suggesting that the two areas are processed differently(Paivio 1975). This is different from propositional theory and mental models asthey presume that verbal and non-verbal stimuli are represented the same in themind. To conclude, it is clear from thepoints discussed that there are very few similarities between dual-code theoryand propositional theory mostly because the theories focus on complete oppositeideas. Propositional theory focuses on arbitrary propositions and idealises theidea of perception being non-analogous whereas dual-code theory focuses on ourmental representations being analogous of our perceptions and is isomorphic.Mental Models has similarities between both of the theories and acts as a moreinteractionist approach between the two views; it is similar to Dual-CodeTheory as it acknowledges that we do have structural analogies of the realworld and yet is also similar to propositional theory as it recognises that wedo have a deeper understanding of our perceptions.
There are comparisons to bemade between all three theories however, as they are all separate theories andall have different beliefs on how we use mental representations.