Dual-coding theory, a theory of cognition, was hypothesised by Allan Paivio of the University of Western Ontario in 1971. In developing this theory, Paivio used the idea that the formation of mental images aids in learning.
According to Pavio –
”Human cognition is unique in that it has become specialised for dealing simultaneously with language and with nonverbal objects and events.”
According to Paivio, there are two ways a person could expand on learned material:.
Verbal associations and Visual imagery
Dual-coding theory postulates that both visual and verbal information is used to represent information.
Visual and verbal information are processed differently and along distinct channels in the human mind, creating separate representations for information processed in each channel.
The mental codes corresponding to these representations are used to organise incoming information that can be acted upon, stored, and retrieved for subsequent use.
Both visual and verbal codes can be used when recalling information.
For example, say a person has stored the stimulus concept “dog” as both the word ‘dog’ and as the image of a dog.
When asked to recall the stimulus, the person can retrieve either the word or the image individually, or both simultaneously.
If the word is recalled, the image of the dog is not lost and can still be retrieved at a later point in time.
The ability to code a stimulus two different ways increases the chance of remembering that item compared to if the stimulus was only coded one way.
Limitations of Dual-coding theory
- Dual-coding theory does not take into account the possibility of cognition being mediated by something other than words and images.
- Not enough research has been done to determine if words and images are the only way we remember items, and the theory would not hold true if another form of codes were discovered.
- It is only valid for tests on which people are asked to focus on identifying how concepts are related.
- If associations between a word and an image cannot be formed, it is much harder to remember and recall the word at a later point in time.
- While this limits the effectiveness of the dual-coding theory, it is still valid over a wide range of circumstances and can be used to improve memory.
Types of Codes
Analogue codes are used to mentally represent images.
Analogue codes retain the main perceptual features of whatever is being represented, so the images we form in our minds are highly similar to the physical stimuli.
They are a near-exact representation of the physical stimuli we observe in our environment, such as trees and rivers.
Symbolic codes are used to for mental representations of words.
They represent something conceptually, and sometimes, arbitrarily, as opposed to perceptually.
Similar to the way a watch may represent information in the form of numbers to display the time, symbolic codes represent information in our mind in the form of arbitrary symbols, like words and combinations of words, to represent several ideas. Each symbol (x, y, 1, 2, etc.) can arbitrarily represent something other than itself.
Support for Dual-coding theory
Many researchers have agreed that only words and images are used in mental representation.
Supporting evidence shows that memory for some verbal information is enhanced if a relevant visual is also presented or if the learner can imagine a visual image to go with the verbal information.
Likewise, visual information can often be enhanced when paired with relevant verbal information, whether real-world or imagined.
This theory has been applied to the use of multimedia presentations.
Because multimedia presentations require both spatial and verbal working memory, individuals dually code information presented and are more likely to recall the information when tested at a later date.
Participants, however, more readily recalled the sequential order of the words, rather than the sequence of pictures.
These results supported Pavio’s hypothesis that verbal information is processed differently from visual information and that verbal information was superior to visual information when sequential order was also required for the memory task.
Lee Brooks conducted an experiment that provided additional support for two systems for memory.
This supported the idea of two codes used to mentally represent information.
Dual-coding theories complement a dual-route theory of reading.
When people read written information, dual-route theory contends that the readers access orthographic and phonological information to recognize words in the writing.
It also has had implications for cognitive robotics.
Cognitive Neuroscience Support
Two different methods have been used to identify the regions involved in visual perception and visual imagery.
Cerebral blood flow allows researchers to identify the amount of blood and oxygen traveling to a specific part of the brain, with an increase in blood flow providing a measure of brain activity.
An event related potential can be used to show the amount of electrical brain activity that is occurring due to a particular stimulus.
Researchers have used both methods to determine which areas of the brain are active with different stimuli, and results have supported the dual-coding theory.
Dual-coding theory is not accepted by everyone.
John Anderson and Gordon Bower proposed an alternative method – the propositional theory – of how knowledge is mentally represented.
The propositional theory claims that mental representations are stored as propositions rather than as images.
Here, proposition is defined as the meaning that underlies the relationship between concepts.
This theory states that images occur as a result of other cognitive processes because knowledge is not represented in the form of images, words, or symbols.
The common coding theory has also been proposed as an alternative to dual coding theory.
The common coding theory looks at how things we see and hear are connected to our motor actions.
It claims that there is a common code that is shared between perceiving something and the respective motor action.