Ashley Choy and Andrew Jun Lee (graduate student mentor)
Close your eyes and try to imagine any kind of object. Now visualize how much of it you can see: its colors, depth, clarity, etc. The extent to which you can visualize the object relies on your capacity for mental imagery. Mental imagery has long been the object of scientific inquiry. Traditionally, mental imagery has been understood as a form of conscious experience. In the same way that we consciously experience an object through visual perception, mental imagery is analogous to perception without sensory input. “We use the term ‘mental imagery’ to refer to representations and the accompanying experience of sensory information without a direct external stimulus” (Pearson et al., 2015). Here I discuss the intricate relationship between mental imagery and intelligence.
Mental imagery is a ubiquitous tool of daily life. It is particularly useful for planning and foresight. For instance, we imagine a basketball swish before we throw the ball. We conjure victory before it happens. The link between imagery and intelligence is suggestive of a shared cognitive basis, but its psychological underpinnings are not well understood. Various aspects of mental imagery may be related to intelligence. Of special note are spatial awareness and visuospatial reasoning, which include the ability to perceive, analyze, and mentally manipulate visuospatial information. Individuals with a high affinity for spatial manipulation are likely able to perform a variety of feats: rotating complex objects, navigating mental maps, and visualizing complex architectural structures.
If mental imagery is a key component of spatial intelligence, individuals with a weaker capacity for mental imagery should struggle on spatial reasoning tasks. As an extreme case, consider aphantasic patients, or individuals who lack the capacity for mental imagery. Contrary to this prediction, aphantasic individuals have higher mental rotation task accuracy compared to individuals with normal self-reported mental imagery (Pounder et al., 2018). This superiority is robust across levels of task difficulty, but interestingly, aphantasic individuals take longer to do the task than controls. The authors of this study conclude that aphantasic individuals may be using a different strategy to perform mental rotation than individuals with intact mental imagery, though it remains unclear what strategy is used. Spatial intelligence should not depend on mental imagery if this alternative strategy does not involve imagery.
That aphantasic patients may be using a different strategy to solve mental rotation tasks is consistent with studies of recall. In one study by Bainbridge (2021), participants were shown different sets of photographs of rooms with differently placed objects and were asked to recall the locations of these objects by having them draw the rooms from memory. Like controls, aphantasic individuals were able to recall the locations of the objects in these rooms. But like the study about mental rotation, aphantasic patients displayed a slightly different, more nuanced pattern of results, suggestive of a different cognitive strategy than controls. First, the extent of recall was more limited in detail compared to controls. Second, they were less likely to confabulate false memories about the specific detailing of these objects. The authors of this study argue that aphantasic patients may be using a form of verbal association rather than mental imagery to encode object location. The proposed explanation is that verbal associations are less extensive at encoding object memories than mental imagery. Aphantasic participants may show a greater dependence on symbolic information as they were seen to have more text in their drawings compared to the control group. Thus, this greater reliance on text could signify a connection between memory and verbal coding.
These two studies on mental rotation and recall suggest that mental imagery is not a strong determinant of spatial intelligence. As both studies posit, spatial reasoning and recall as typically performed by mental imagery may be approximated in ways that do not actually require imagery. Bracketing spatial intelligence aside, it’s possible that mental imagery has a tighter link to other facets of intelligence such as those that involve mental simulation, or the ability to generate a continuous sequence of causally related events that converge onto an outcome. Simulation is often recruited in visual problem-solving, like when generating moves in chess or predicting the way a stack of blocks will fall. Thus, individuals who are able to mentally visualize problems may fare better in searching through solution spaces that require visual simulation.
However, Dawes and colleagues (2022) demonstrated that aphantasic individuals were unable to generate as many episodic details for hypothetical future events that have not yet happened. This reduction appears causally linked to poor mental imagery: the fewest kinds of details were visual in nature, fewer perceptual words were used to describe their simulation overall, and aphantasics reported lower ratings of the experienced richness or thoroughness of their simulation. Although there is some evidence to suggest that facilitating imagery in problem-solving improves performance, specifically for mathematics problems (Douville et al., 2003), the evidence for the link between aphantasics’ simulation ability and problem-solving remains unclear. It is reasonable to suspect that the poor simulation capability of aphantasics manifests in poor problem-solving performance.
In conclusion, the intricate relationship between mental imagery and intelligence involves various dimensions, including spatial intelligence, memory, simulation, and visuospatial reasoning. Mental imagery emerges as a multifaceted tool with implications for different aspects of cognitive function. While it is not the sole indicator of intelligence, a strong capacity for mental imagery may correlate with excellence in diverse intellectual endeavors, underscoring its supportive role in the broader landscape of human intelligence.
References
Bainbridge, W. A., Pounder, Z., Eardley, A. F., & Baker, C. I. (2021). Quantifying aphantasia through drawing: Those without visual imagery show deficits in object but not spatial memory. Cortex, 135, 159-172.
Dawes, A. J., Keogh, R., Robuck, S., & Pearson, J. (2022). Memories with a blind mind: Remembering the past and imagining the future with aphantasia. Cognition, 227, 105192.
Douville, P., & Pugalee, D. K. (2003). Investigating the relationship between mental imaging and mathematical problem solving. In Proceedings of the International Conference of Mathematics Education (pp. 62-67).
Pearson, J., Naselaris, T., Holmes, E. A., & Kosslyn, S. M. (2015). Mental imagery: functional mechanisms and clinical applications. Trends in Cognitive Sciences, 19(10), 590-602.