Category Recognition

In this video I consider how language can help us to organize thought and create more precise concepts and categories. This raises the question of how we recognize new stimuli as being part of a particular category. Protoype theory suggests that we mentally compare new stimuli to a prototype or most-typical example for a particular category. Exemplar theory suggests that we use prototypes in addition to our memory for other examples of exceptions and variations, though this process will be slower.


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Video Transcript:

Hi, I’m Michael Corayer and this is Psych Exam Review. In the previous video I talked about this complex relationship between language and thought.

In this video I want to provide one way of thinking about this relationship in that language helps us to organize our thought. It helps us to create more precise concepts and categories to make sense of the world. Of course animals can also create concepts and categories without using language and we saw this in the video on abstract learning I talked about pigeons who were taught to peck at pictures of chairs and then they could be shown a new picture of a chair that they’ve never seen before and they would correctly peck at it.

This shows that they have some understanding of this idea of the category of chairs. Now this makes sense that animals should be able to do this without using language, after all, they need to be able to recognize new stimuli that they’ve never seen before. They need to be able to see a new item of food that they’ve never seen before and recognize that it’s food or they need to see a predator and recognize that it’s a predator even though it’s not a particular predator that they’ve seen before.

Ok so how do we go about deciding when something is part of a particular category? How do we recognize something as being a chair? How is it that we can walk into IKEA, see a chair that we’ve never seen before, and immediately know that it’s a chair.

Well, one way of thinking about this is we can say, well maybe we have rules that we follow. Maybe we could come up with a list of rules of chairness. Ok, if it’s a chair then it will meet these criteria. This seems reasonable. The problem we have is that it’s hard to figure out what those rules would be. As soon as you come up with a rule you can probably think of an exception to it that you would still recognize as a chair. You might say, okay, well it has to have four legs. Well you know that’s not necessarily true. I mean it could have a solid base and I would still recognize it. Ok, well you know does it have to have a hard or soft surface? Well that doesn’t matter, it could have either. Or sharp or rounded corners? Well that doesn’t really matter either.

What you find is that it’s really hard to come up with a list of rules of chairness.. So we probably aren’t using rules when it comes to recognizing parts of a category. Instead we’re probably using some general guidelines where we have some features that we recognize as being important for a particular category but we also recognize that there’s exceptions and there’s variation.

To demonstrate this, I’d like you to draw a picture of a bird. So pause the video for a few seconds and just quickly sketch a bird. All right now I’m going to draw a picture of a bird and we’ll see if my drawing is similar to what you came up with. So if somebody asked me to draw a bird I would probably draw something like this.

Ok, so here’s my bird. Not a great bird but it’s enough of a bird I guess and maybe this is similar to what you’ve drawn. Hopefully it is and so what I’ve tried to show is I’ve tried to draw a prototype of a bird. A prototype refers to something that’s sort of the best example of a bird, right? It’s the most bird-like bird that I could draw, right? And so the idea here is that it has sort of all of the characteristic features that we associate with this category of bird.

Now you probably drew something similar to this. You probably didn’t draw a penguin or an ostrich. Now those are just as much birds as the bird that I’ve drawn but they’re not as prototypical. They have a lot of features that don’t quite fit with the general idea of what a bird is.

So what prototype theory suggests is that when we see a new stimulus we compare it to a prototype to determine if it’s part of a category. And again, the prototype is this idea of the most typical example. Ok, so when I see some new thing that might be a bird I mentally compare it to something like this; something small, has feathers, can fly, has twig-like legs, a small beak, right? These are the things I associate as being sort of prototypical bird features and something to compare a new stimulus to those in order to identify it.

Now this idea of how we recognize parts of a category, we can see in children when they do this. We can see, you know, if a child is taught this is a doggy right? Ok, doggy and then later they see a cat and they say doggy. Well what’s happening there? What’s happening is they’re actually correct, I mean those things are part of the same category if you think of that category as being small furry things that you can play with and pet.

In that case they are part of the same category and then what we have to teach the child is well actually you know linguistically we have some different labels for those. We divide them up into sort of a more precise version of that. We say okay well these ones are dogs and these ones are cats. Yes we can put them overall in the category of pets but we’re going to be more specific here and doggy refers specifically to these types here and cat refers to these types here.

But in terms of recognizing the category of this new item the child is actually pretty much correct in thinking of doggy as being these small furry things that you play with. Ok so how do we go about recognizing something that’s different from a prototype, right?

So sometimes the idea of prototype theory is that you know we’re going to bring something to mind and compare it to this prototype and recognize whether it’s part of a category or not. But of course the exceptions are also recognized. So how does this happen?

This brings us to what’s called exemplar theory. What exemplar theory says is that we have prototypes that we mentally compare to but that we also have our memory and we can also bring to mind other exceptions that we’ve encountered. So we can, you know, if we want to recognize whether some new stimulus is a bird or not, we compare it to a prototype of a bird but we might also consider how it compares to a penguin or an ostrich or a peacock, right? We can bring to mind our memory for exceptions and those will help us in making this determination.

The problem is this is going to be a little bit slower right? When something is closely matched to a prototype we can see it and recognize it immediately. When something has more exceptions and needs to be thought of in terms of other variations then that’s necessarily going to be a slower process. It’s going to take us a little bit longer to decide if something is part of this category.

Ok, so that’s prototype theory and exemplar theory, I hope you found this helpful, if so, please like the video and subscribe to the channel for more.

Thanks for watching!