Definition:
An internal image, in the cognitive science sense, is a mental representation of visual information that is generated or recalled in the absence of direct sensory stimuli. It is part of the broader concept of internal representations, which are mental constructs that encode information about the world, experiences or abstract concepts.
Discussion:
- Forms of Internal Representations:
a) Visual representations:
These include mental images that are similar to visual experience. Kosslyn et al. (2006) argue that visual mental images are based on similar neuronal mechanisms as visual perception itself [1].
b) Propositional representations:
These represent information in an abstract, language-like form. Pylyshyn (2002) argues that many cognitive processes are based on propositional rather than pictorial representations [2].
c) Procedural representations:
These represent action sequences or skills. They are often implicit and difficult to verbalise (Squire, 2004) [3].
d) Emotional representations:
These encode affective states and can interact with other forms of representation (Damasio, 1994) [4].
e) Multimodal representations:
These integrate information from different sensory modalities (Barsalou, 2008) [5].
- Characteristics of Visual Representations:
a) Spatial properties:
Visual representations often preserve spatial relationships between objects (Kosslyn, 1980) [6].
b) Level of detail:
They can vary in their level of detail, from vague outlines to high-resolution ‘pictures’ (Pearson et al., 2015) [7].
c) Manipulability:
Mental images can often be mentally rotated, enlarged or otherwise manipulated (Shepard & Metzler, 1971) [8].
d) Subjective vividness:
The experienced clarity and vividness of mental images varies between individuals and situations (Marks, 1973) [9].
- Neurological ‘Building Blocks’ of Neuronal Representations:
a) Neuronal ensembles:
Groups of neurons that fire together and encode specific information (Hebb, 1949) [10].
b) Synaptic connections:
The strength and structure of synaptic connections encode information and enable learning (Kandel et al., 2000) [11].
c) Oscillatory activity:
Synchronised neuronal oscillations play a role in the integration of information and the formation of coherent representations (Buzsáki & Draguhn, 2004) [12].
d) Topographical maps:
Topographic maps that preserve spatial relationships exist in many brain areas, especially in the visual system (Wandell et al., 2007) [13].
e) Distributed coding:
Complex representations are often encoded by distributed patterns of activity across many neurons (Haxby et al., 2001) [14].
f) Predictive coding:
Neural networks generate predictions about expected inputs that are compared with actual sensory inputs (Rao & Ballard, 1999) [15].
- Current Research and Challenges:
a) Individual differences:
Research into aphantasia, the inability to generate mental images at will, has raised new questions about the nature and necessity of visual representations (Zeman et al., 2015) [16].
b) Artificial neural networks:
The development of models such as DeepDream has provided new insights into the possible structure of visual representations (Mordvintsev et al., 2015) [17].
c) Consciousness and representation:
The relationship between neural representations and conscious experience remains an active area of research (Dehaene et al., 2014) [18].
d) Multimodal integration:
Research into how different forms of representation are integrated in the brain is of increasing interest (Spence & Deroy, 2013) [19].
To summarise, inner images and visual representations are complex cognitive phenomena that are based on a variety of neural mechanisms. Their study offers important insights into the functioning of the human mind and has implications for areas such as memory, problem solving and creativity.
[Excerpt from chapter 4 of the manuscript]
In brain research, it is known that inner images (representations) arise from the interaction of different brain regions. For example, as soon as the desire for water arises in the frontal lobe, a part of the brain responsible for higher cognitive functions such as decision-making, problem-solving, planning, social behaviour and the control of voluntary movements, a visual impression is created in the posterior part of the brain in the visual cortex of the occipital lobe, a region above the cerebellum.
The question of how an overall impression can arise that does not require an external stimulus, as in the case of imagination, is still a mystery. As mentioned, the brain patterns activated when seeing an object and when imagining the same object hardly differ.
The question of how an internal image is created from the estimated 10 million stimuli per second on the retina of the human eye is just as difficult to grasp, as there are no neuronal clues for the formation of an image within the brain. Neurones have no function like pixels in the sense of an image cell in the construction of a digital screen. No specialised neuron types are known for this purpose. Furthermore, neither fixed nor hierarchical connection patterns of neurons are known for creative processes. Instead, the connection patterns of neurons are generally designed for parallelisation, reciprocity and decentralised distribution. This enables the brain to adaptively perform tasks from damaged brain regions in other brain regions.
Literature:
[1] Kosslyn, S. M., Thompson, W. L., & Ganis, G. (2006). The case for mental imagery. Oxford University Press.
[2] Pylyshyn, Z. W. (2002). Mental imagery: In search of a theory. Behavioral and brain sciences, 25(2), 157-182.
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[4] Damasio, A. R. (1994). Descartes’ error: Emotion, reason, and the human brain. Putnam.
[5] Barsalou, L. W. (2008). Grounded cognition. Annual review of psychology, 59, 617-645.
[6] Kosslyn, S. M. (1980). Image and mind. Harvard University Press.
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[8] Shepard, R. N., & Metzler, J. (1971). Mental rotation of three-dimensional objects. Science, 171(3972), 701-703.
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[10] Hebb, D. O. (1949). The organization of behavior: A neuropsychological theory. Wiley.
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[13] Wandell, B. A., Dumoulin, S. O., & Brewer, A. A. (2007). Visual field maps in human cortex. Neuron, 56(2), 366-383.
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[15] Rao, R. P., & Ballard, D. H. (1999). Predictive coding in the visual cortex: a functional interpretation of some extra-classical receptive-field effects. Nature neuroscience, 2(1), 79-87.
[16] Zeman, A., Dewar, M., & Della Sala, S. (2015). Lives without imagery–Congenital aphantasia. Cortex, 73, 378-380.
[17] Mordvintsev, A., Olah, C., & Tyka, M. (2015). Inceptionism: Going deeper into neural networks. Google Research Blog.
[18] Dehaene, S., Charles, L., King, J. R., & Marti, S. (2014). Toward a computational theory of conscious processing. Current opinion in neurobiology, 25, 76-84.
[19] Spence, C., & Deroy, O. (2013). How automatic are crossmodal correspondences? Consciousness and cognition, 22(1), 245-260.