Perception, we usually assume, delivers us the world, and it’s then up to us to decide what to believe. Ideally, we simply match our beliefs to what we perceive. But philosopher Neil Mehta argues that it’s not as simple as this. Your thoughts and beliefs and prejudices all influence perception itself, playing a role in constructing your experience. This means, Mehta argues, that your perceptions can be more or less rational, and even more or less moral, and that we cannot simply trust all that we see, hear, touch and smell.

Some things, like apples and fire hydrants, are red. Some things, like frogs and blueberries, are other colors. But some things, like the number 4 and the concept of justice, aren’t any color at all—they aren’t the kinds of things that can be colored.

Similarly, some things are rational, like believing that 1 + 1 = 2 or drawing conclusions that are well-supported by your evidence. And some things are irrational, like believing that 1 + 1 = 3 or jumping to conclusions that are unsupported by your evidence. But some things cannot be assessed for rationality at all. The feeling of itchiness in your elbow is neither rational nor irrational—it just is.

What about conscious perceptions, like your experience of seeing an apple, hearing a violin, or smelling vanilla—can these be rational/irrational? The natural answer is no. For surely if a mental state can be rational/irrational, then that state can, in principle, be revised in light of new information. And although you can, when you receive new information, revise your belief that there is a red apple in front of you, you cannot revise your perception of a red apple in front of you. At best, you can close your eyes.

Despite the appeal of this argument, I think that many conscious perceptions might be rational/irrational after all. Here’s why.

When we perceive things, we often apply concepts to them. When you look around your office, you might see a desk and a laptop, and you will conceptualize them as a desk and a laptop. You cannot help yourself: conceptualizations like this happen automatically.

Philosopher Eric Mandelbaum has persuasively argued, on the basis of substantial scientific evidence, that conceptualization can occur within perception itself. The idea is that you don’t first consciously perceive a scene and then conceptualize it. Instead, your visual system packages the conceptualization of the scene into your conscious perception of it. At the conscious level, you receive both things, bundled together, at the same time.

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In one telling experiment cited by Mandelbaum and conducted by Potter et al., subjects were presented with a word, like “flowers,” followed by a series of images, and they had to say whether the image matched the word. The key feature of the experiment was that each image was presented for just 13 milliseconds—that’s about 1/8 of the time it takes to blink. Even so, subjects performed at well above chance. But feedback processing just within the visual system takes about 50 milliseconds, and post-perceptual feedback processing takes much longer. So this is evidence that the conceptualizations in these cases were occurring perceptually (in the visual system), not in post-perceptual cognition.