A post by Anna Abraham.

A 1969 treatise by Jeremy Walker begins as follows. “One of the most striking features of nearly all philosophical psychologies has been their failure to deal at all adequately with imagination … This 'conspiracy of silence' is puzzling, and I can think of no hypothesis to account for it. For it cannot be denied that imagination is a power, or web of powers, which plays a central part in the structure of human activity and consciousness; and so a failure to consider this power adequately must lead to a philosopher's giving a distorted, or one-sided, account of the distinctively human. For the powers of imagination are clearly related in a close and complex way with the other central human powers, such as belief, the passions, intention and the will. And it follows that any philosopher who systematically underplays the role of imagination must at some point introduce a corresponding distortion into his account of, say, the role of belief or the role of intention in human affairs” (Walker, 1969: 575) .

Substitute the term ‘philosopher’ with ‘psychologist’ in this passage, and the accusation holds water. Down to the present day.  

Our understanding of the workings of the human mind is largely based on theory and research that follows the approaches and methods of experimental psychology. Historically then, psychological functions that could be more readily tested under laboratory conditions, such as perception, attention and learning, dominated the discourse. In doing so, they fundamentally shaped how we construe the human mind, and investigations of the same ever since have been constrained by the implicit assumptions of these domains. Even contemporary influential theoretical frameworks, such as predictive coding models (Clark, 2013; Feldman & Friston, 2010) that focus on delineating the perception-action cycle of the brain where the underlying mechanisms take the form of receptive-predictive loops, have their roots in the classic S-O-R model. After all, they focus on how organisms make sense of and interact with the external world based on the stimulus information arriving at the senses and the ensuing response patterns that are generated in a given context.

What is largely omitted from these discussions is a rigorous consideration of our pesky internal world (beyond interoception) and how its workings factor into these neat models. The imagination is exceedingly complex, defies comprehensive definition, and does not easily lend itself to empirical enquiry. Which is probably why it has been ignored for most part. What this means though is that theories of the mind have been churned out without having to consider the full gamut of the human experience. One could go so far as to say that the quintessential piece of the picture is missing given that we spend a substantial proportion of our daily lives occupying imaginative spaces. For instance, conservative estimates suggest that we find ourselves in states of mind wandering, fantasy, reverie or daydreaming over “at least 25-50% of our waking lives” (Konishi & Smallwood, 2016) . When asked to reveal the content of what occupied their minds over periods of rest when there was no task to perform during an experiment, retrospective thought sampling procedures revealed that participants report not thinking about anything only 5% of the time. Instead, they spontaneously engaged in internal mentation on a range of themes, including past events and future possibilities (Andrews-Hanna, 2012) . Indeed, even in contexts that require constant perceptual-action monitoring, such as while driving a car, high incidences of mind wandering (almost 70%) are reported when driving under predictable conditions (Baldwin et al., 2017) . If we were to also factor in the proportion of time spent engaging the imagination through other avenues, such as during deliberate internal mentation or when construing fictional worlds while reading, it is clear that most of our waking life is spent in realms of the imagination.

The absence of a comprehensive theoretical framework for the human mind in which the imagination is clearly given its due leaves us in a quandary. Where can we begin if we are to develop a keener understanding of the imagination? One approach is to delve into the neuroscientific literature on different aspects of imagination, such as imagery, mental state reasoning and creativity, and examine the patterns of similarities and differences that emerge (e.g., Daselaar, Porat, Huijbers, & Pennartz, 2010; Jung & Vartanian, 2018; Spreng, Mar, & Kim, 2009) . Concurrently, we can also refer to the philosophical literature on the same to reflect on how best to define and conceive of different clusters of imaginative operations (e.g., Gendler, 2013; Stevenson, 2003) . Adopting this form of reasoning culminated in the formulation of a novel neurophilosophically informed framework for the imagination in which a five-part classification was put forward (Abraham, 2016) .

Aspects of the imagination that encompass perceptual and motor forms of mental imagery fall into the category of mental Imagery-based Imagination. Much of the focus here has been in determining the nature of mental representations as well as the extent of the overlap between the brain basis of perception (e.g., visual, auditory, musical, motor) and imagery of the same. The evidence overwhelmingly indicates strong parallels between the mechanisms underlying perception and imagery as corresponding regions of sensory and motor brain networks are commonly engaged in both.

While mental-imagery based imagination draws its impressions from the external milieu, the internal milieu is the source material that is drawn upon in processes of imagination that are involved in the aesthetic response across modalities (in the appreciation of visual arts, music, food, and so on). These therefore belong to the category of phenomenology-based imagination. Brain networks that are involved in interoceptive awareness, emotional responsiveness and reward processing are preferentially activated during aesthetic appreciation and engagement.

Operations such as mental state reasoning or theory of mind, episodic and autobiographical memory, episodic future thinking, moral cognition and self-referential processing are classified as forms of intentionality-based imagination given that all of them engage the default mode network of the brain. Their underlying commonality is postulated to be that each of these states trigger processing that is mainly recollective in nature with the aim of arriving at the best possible explanation of a given situation from the standpoint of what fits best with one’s own views.

In contrast, when a context necessitates moving beyond what is known to seek new solutions, explanations or expressions, processes of novel combinatorial-based imagination are called into play. Operations of interest include creativity, counterfactual reasoning and hypothesis generation. A complex interplay between several brain networks are drawn upon here including the default mode network, the central executive network and the semantic cognition network.

The final category is that of altered states of imagination which encompass ordinary states that each of us routinely experience (e.g., dreaming) or can choose to experience (e.g., hypnosis, meditation) as well as atypical states that come about via temporary or permanent neurological insult (e.g., out-of-body experiences, delusions, hallucinations). These states come to pass as a result of local or global disruptions within different brain networks including the default mode network, the central executive network and sensory-motor networks.

The advantages of this preliminary framework are that is it cross-disciplinary, comprehensive and data driven. It therefore stands to serve well as a springboard for further advances in our understanding of the imagination. A vital next step would be to develop common models for imaginative and non-imaginative facets of psychological function. Viable ideas in relation to the same are scarce and speculative (Abraham & Bubic, 2015) . But the pursuit to understand and explain human nature requires that we take on the imagination in all its convoluted complexity. For without it, any account of the mind is necessarily incomplete.

REFERENCES

Abraham, A. (2016). The imaginative mind. Human Brain Mapping, 37(11), 4197–4211. https://doi.org/10.1002/hbm.23300

Abraham, A., & Bubic, A. (2015). Semantic memory as the root of imagination. Frontiers in Psychology, 6. https://doi.org/10.3389/fpsyg.2015.00325

Andrews-Hanna, J. R. (2012). The brain’s default network and its adaptive role in internal mentation. The Neuroscientist, 18(3), 251–270. https://doi.org/10.1177/1073858411403316

Baldwin, C. L., Roberts, D. M., Barragan, D., Lee, J. D., Lerner, N., & Higgins, J. S. (2017). Detecting and Quantifying Mind Wandering during Simulated Driving. Frontiers in Human Neuroscience, 11. https://doi.org/10.3389/fnhum.2017.00406

Clark, A. (2013). Whatever next? Predictive brains, situated agents, and the future of cognitive science. Behavioral and Brain Sciences, 36(03), 181–204. https://doi.org/10.1017/S0140525X12000477

Daselaar, S. M., Porat, Y., Huijbers, W., & Pennartz, C. M. A. (2010). Modality-specific and modality-independent components of the human imagery system. NeuroImage, 52(2), 677–685. https://doi.org/10.1016/j.neuroimage.2010.04.239

Feldman, H., & Friston, K. J. (2010). Attention, Uncertainty, and Free-Energy. Frontiers in Human Neuroscience, 4. https://doi.org/10.3389/fnhum.2010.00215

Gendler, T. (2013). Imagination. In E. N. Zalta (Ed.), The Stanford Encyclopedia of Philosophy (Fall 2013). Retrieved from http://plato.stanford.edu/archives/fall2013/entries/imagination/

Jung, R. E., & Vartanian, O. (Eds.). (2018). The Cambridge Handbook of the Neuroscience of Creativity. Cambridge: Cambridge University Press.

Konishi, M., & Smallwood, J. (2016). Shadowing the wandering mind: how understanding the mind-wandering state can inform our appreciation of conscious experience. Wiley Interdisciplinary Reviews. Cognitive Science, 7(4), 233–246. https://doi.org/10.1002/wcs.1392

Spreng, R. N., Mar, R. A., & Kim, A. S. N. (2009). The common neural basis of autobiographical memory, prospection, navigation, theory of mind, and the default mode: a quantitative meta-analysis. Journal of Cognitive Neuroscience, 21(3), 489–510. https://doi.org/10.1162/jocn.2008.21029

Stevenson, L. (2003). Twelve Conceptions of Imagination. The British Journal of Aesthetics, 43(3), 238–259. https://doi.org/10.1093/bjaesthetics/43.3.238

Walker, J. (1969). Imagination and the Passions. Philosophy and Phenomenological Research, 29(4), 575–588. https://doi.org/10.2307/2105541