A post by Dan Cavedon-Taylor

That night, Wang sat in his study and admired the few landscape photographs, his works he was the most proud of, hanging on the wall. His eyes fell on a frontier scene: a desolate valley terminating in a snowcapped mountain. On the nearer end of the valley, half of a dead tree, eroded by the vicissitudes of many years, took up one-third of the picture. In his imagination, Wang placed the figure that lingered in his mind at the far end of the valley. Surprisingly, it made the entire scene come alive, as though the world in the photograph recognized that tiny figure and responded to it, as though the whole scene existed for her.

He then imagined her figure in each of his other photographs, sometimes pasting her two eyes into the empty sky over the landscapes. Those images also came alive, achieving a beauty that Wang had never imagined. Wang had always thought that his photographs lacked some kind of soul.

Now he understood that they were missing her.

--Liu Cixin, The Three-Body Problem (translated by Ken Liu)

Cognitive penetration is said to occur if what one believes or desires, or expects, etc. directly affects how one perceives. For instance, perhaps believing someone is angry makes their neutral face look as if it is expressing anger (Siegel 2012). Maybe a desire for wealth makes coins look larger than they would otherwise (Stokes 2012; Bruner & Goodman 1947). And feasibly, believing that a piece of meat came from a factory farmed animal may make it taste extra salty (Anderson & Barrett 2016).

There is substantial disagreement over whether cognitive penetration does in fact occur.

A post by Dan Cavedon-Taylor.

One issue that has recently gained attention in the literature on mental imagery is the existence of perceptual-imagery hybrids. Consider the following:

Seeing Constellations: Seeing a constellation in the night sky may be partially a matter of projecting into one’s visual experience imagery of lines connecting stars (Briscoe 2011)

Seeing Cats: Seeing a cat that is partially occluded by a picket fence, as a whole object, may be partially a matter of projecting into one’s visual experience imagery of the occluded parts of the cat (Thomas 2009; Nanay 2010; Kind forthcoming)

Avoiding Skunks: Seeing what path to take to avoid a skunk may be partially a matter of projecting into one’s visual experience the trajectory of the skunk’s spray (Van Leeuwen 2011)

The fact that imagery can combine with perception in these ways seems to tell us something important about the nature of mental images: that they are fundamentally perceptual. After all, what imagery does in these examples is aid perception in discharging its essential functions: tracking the objects before us, identifying the objects before us and guiding our actions with respect to those objects.