The Grain of Vision and the Grain of Attention Henry Taylor jht30@cam.ac.uk Birkbeck June 2017

A puzzle Imagine you’re a neuroscientist. How do you explain consciousness?

A puzzle Some tricky (and well known) issues: Consciousness seems to be in some sense ‘private’ or ‘personal’ or ‘subjective’? Science studies the ‘objective’ and ‘non-private’: that which can be ‘objectively measured’ in some sense.

A puzzle Perhaps start with a more manageable question: What makes the difference between something being unconscious and it being conscious?

The unconscious mind Most of the content of your mind is completely unconscious: Automatic processes: (e.g. regulation of breathing, lots of your action control systems) Repressed beliefs (???????) Unconscious beliefs (Paris is the capital of France).

Unconscious perception We know that when you see something, most of the processing of the information in your brain goes on unconsciously.

From unconscious to conscious. So what marks the difference between the unconscious and the conscious? Attention. ‘consciousness arises when and only when we attend… How do we become conscious? We attend.’ Jesse Prinz. Loads of stuff is unconscious, but when you pay attention to something, this processing raises from the depths of the unconscious and becomes conscious.

Attention and consciousness So, when you pay attention to something, you’re conscious of it. When you don’t, you’re not.

Attention and consciousness Why believe this? When you’re not paying attention, you can miss all sorts of things.

Attention and consciousness

Attention and consciousness

Attention and consciousness

Attention and consciousness Can this be right? Surely it seems like you’re conscious of more than you can pay attention to!

Attention and consciousness This is difficult to judge. It might be that you give a little bit of attention to the whole picture. Also, whenever you ‘check’ whether you’re conscious of something, you inevitably pay attention to it.

Attention and consciousness If we’re going to tease apart attention and consciousness, we need a much more subtle approach. One way: visual crowding.

Visual crowding

Visual crowding

Visual crowding The bottom one is the crucial one. 1) You can’t pay attention to the middle letter in the bottom row. 2) You can still identify it, pick it out from the background, and ‘point at it’ mentally. 3) Because you can do all of these things, we should conclude that you’re conscious of it. 4) Therefore, this is a case of consciousness without attention.

Visual crowding

Visual crowding The ‘grain’ of vision is supposedly finer than the ‘grain’ of attention. Meaning that vision can pick out finer details than attention can. Vision can pick out the middle ‘A’, but attention cannot ‘grab’ it.

Visual crowding My view: this doesn’t demonstrate consciousness without attention at all. My argument: account for the fact that we can identify the middle ‘A’, without saying that we are conscious of it.

Visual crowding: option 1 1st option: ‘flanker substitution’. We mistake the outside letters, the ‘flanker’ for the middle letter. In the case of the top row, if we said the name of a flanker, this would be an incorrect answer. In the case of the bottom row, the answer is ‘correct’, so these mistakes go unnoticed.

Visual crowding: option 2 2nd option: we may not be able to pay attention to the middle ‘A’, but we can pay attention to the group of letters as a whole. We may be conscious of the entire group. Our consciousness may lack the detail for us to be conscious of the middle ‘A’.

Visual crowding: option 2 Even though we cannot consciously see the middle ‘A’, we may have enough information to see one of the flankers, and see that the group is congruous and uniform, and see that it is cluttered (that there are more than two letters there).

Visual crowding: option 2 What do I mean by ‘congruous’? We can tell when a group of items are all alike, and when they are not, just from a glance.

Visual crowding: option 2 What do I mean by ‘cluttered’? We can immediately see when there’s lots of items there, as opposed to just one, just from a glance.

Visual crowding: option 2 Then we could infer: 1) The group contains at least one ‘A’. 2) The group is uniform (all the letters are the same). 3) The group is cluttered (there are more than two letters there). 4) (Therefore) There is another letter there, which is also an ‘A’.

Visual crowding A question: Which account of crowding is better? Block’s: consciousness without attention. Mine: we aren’t really conscious of the middle ‘A’, we ‘work it out’ somehow. Something else…..?

Attention and consciousness Where does this leave us? How can we differentiate attention and consciousness (if at all)? How can we avoid the refrigerator light illusion? What are your intuitions about these cases? Is attention a decent explanation of consciousness?