.png){kind=icon}
Chapter Summary
This chapter examines mental imagery and how we invoke mental pictures or sounds in order to remember and think. An interesting example of this can be observed in time–space synesthesia, which is the case when people experience various units of time (e.g., the months or days of the week) as a spatial pattern that only they can see.
Paivio postulated the dual-coding theory, which argues that images can be represented by both verbal and non-verbal systems. Logogens are the units that are part of the first system, and imagens comprise the latter. Furthermore, Paivio maintained that words that produce a mental image have concreteness. In one of his experiments a high correlation was found between ratings of high concreteness and high imagery. He was also in favour of the theory that the right hemisphere controls imagery and that the left hemisphere is responsible for verbal representation, although this view was later challenged by fMRI studies that used lexical decision tasks for words of varying concreteness.
Imagery has also been used as a mnemonic technique, by employing the method of loci (using bizarre images of objects placed in familiar places), for instance. Distinctiveness has been strongly related to imagery. It has long been found that the most bizarre or distinctive items in a set of common items are better remembered (von Restorff effect). This phenomenon also applies to humour, with more humorous material recalled more easily. Furthermore, people can use the special places strategy; however, since it relies solely on distinctiveness, it is a less reliable aid to memory.
A peculiar aspect of psychology is when a stimulus appropriate to one sense (e.g., a sound) triggers an experience appropriate to another sense (e.g., a colour). This is referred to as synesthesia, a condition that affects as many as one in 200 people. The most common form of synesthesia is coloured hearing (chromesthesia). The cue that brings on such experiences is called an inducer and the response to it is named the concurrent. Synesthetic experiences improve memory for certain stimuli. A modern neurobiological explanation of such phenomena is that what starts out as transient connections in the brain become permanent when a process called apoptosis (neuronal pruning) fails to eliminate improper connections. Considering that even thinking about concepts can lead to synesthetic experiences, people who experience chromesthesia are deemed strong synesthetes. However, even if individuals are not strong synesthetes, they might still show similar cross-modal effects. In fact, most people are weak synesthetes.
An icon is “a snapshot of the information contained in a visual stimulus.” Similar to iconic imagery, eidetic imagery also persists after the removal of the stimulus, however it stays longer than an icon does. Both eidetic imagery and synesthesia are examples of cognitive dedifferentiations, which simply means that processes for typically independent processes are fused. Although it is possible that everyone may possess eidetic imagery to a certain extent, people view ordinary visual memory images differently in their vividness of visual imagery. Furthermore, despite being able to recall many details from eidetic images, these descriptions are generally no more accurate than ordinary memories (i.e., this does not represent photographic memory). Photographic memory as it is commonly understood likely doesn’t exist, although, there has been a single reported case of superb eidetic imagery ability. People vary in their ability to use visual imagery. This has been referred to as the vividness of visual imagery, and can be quantified using a questionnaire called the Vividness of Visual Imagery Questionnaire.
In addition to perceiving images, people can imagine whole objects that move. For example, participants use mental rotation to conclude whether or not two objects are the same. Furthermore, it was found that objective distance is preserved in people’s mental images. It was then argued that categorical distance was another important factor that contributes to the time it takes to scan through a mental image. Images can also be used as anticipations. Moreover, they can show emergent properties whilst being constructed. It has often been maintained that imagery is an analog form of representation. In contrast to mental rotation, there are egocentric perspective transformations, where people imagine themselves moving in a mental environment, and the spatial framework suggests that people imagine themselves having one vertical and two horizontal dimensions.
Although there has been a great deal of research on imagery, there is some debate regarding the nature of the representation of knowledge. One theory is called propositional knowledge, and it suggests that mental images are epiphenomenal. That is, images serve no function and are simply a by-product of cognitive processing. Pylyshyn, a proponent of this approach, suggests that images are a result of imagining something as if you were seeing it and thus susceptible to error. Tolman proposed that behaviour is determined by cognitive maps. Another view is that people use an egocentric frame of reference to orient themselves. By adopting this technique, they can also use path integration. Overall, people have mental models for many situations.
Throughout the chapter the focus was on visual imagery but imagery can also involve other sensory modalities as is the case with auditory imagery. Auditory imagery is the conscious experience of sound without external stimulation of the auditory receptor cells. One form of auditory imagery are earworms, in which short catchy pieces of music get stuck in our heads.
Chapter Objectives
- To review experimental evidence for Paivio’s dual-coding theory.
- To examine how synesthesia and eidetic imagery relate to ordinary imagery.
- To outline the role of distinctiveness in memory.
- To distinguish mental rotation, mental scanning, and egocentric perspectives.
- To identify the basic properties of cognitive maps.
- To explore auditory imagery and the brain areas involved in auditory imagery