Next, for this third lecture on perception, I'm going to talk about Gestalt principles of perception. And this is a form of top-down processing. More specifically, it's how we organize our perceptions into unified and meaningful, holistic experiences.
So rather than see little... you look at an image and see a bunch of bits and pieces together and then you try to make sense of it we see them as one more holistic unit and that that applies also it's not just vision it applies to sounds and it applies to you know movement feelings everything so it's it's a way of organizing our senses and our and making them into more complete entities And this makes sense from an efficiency perspective. So the series of examples I'm going to give you in terms of the principles of perception, they're all based on this law of simplicity.
Every stimulus pattern is seen as the simplest possible structure. And from an evolutionary perspective, if we want to live in the world, look around, listen to things, smell things, touch things. We want to be able to figure out what's going on around us quickly, efficiently, so that we can react and act in the most effective manner. And one of the ways to do that is to look for simple structures and holistic patterns.
And if we don't do that, it might take us a very long time to figure out what we're even looking at or what we're hearing or what we're smelling or what we're touching. And by the time we figured it out, we might be dead from an evolutionary, like historical perspective. So here we go.
So law of simplicity guides these. So I'm going to talk about five different principles of perception. Proximity, closure, similarity, continuity and common fate. There's actually more, but these are the five I'm going to talk about. Maybe I should call them the famous five.
I don't know. Proximity. And each of these is really quite simple.
Things near each other tend to be grouped together. So I suspect that most of you see three sets of four red dots. I doubt very much anybody perceived, you know, the first dot in each.
you know little grouping as one unit and the second dots as the next unit and the third set of red dots in the row as the third unit that's not how you saw this pattern i'm sure similarly the blue the blue were right beside each other you probably saw a square of blue dots columns and rows they're all the same so proximity has a fairly strong effect on how we see the world and we sort of and it's almost automatic and so for three sets of red dots one set of blue dots. That's the deal. So it's just a relatively automatic way of perceiving the world. Closure.
The brain fills in gaps to perceive complete forms. So I'm sure most of us thought when we saw the, you know, the green line that it was a triangle, that the blue lines were a face. Doesn't matter if there's no ear or hair showing or, you know.
we recognize it as a head. It's a complete, you know, basically we assume this is the person's head and the letter E. Even though it's not technically finished, I think we all see the letter E.
So this closure principle is also a simplifying method. Like, so, okay, so let's draw the conclusion quickly. What are we dealing with?
We don't have to spend a lot of time wondering, well, it's technically not connected, you know, so it's not really a triangle. It's basically a triangle, right? So we can make a decision quickly and definitively knowing what we're working with.
Very similar to proximity is similarity, I guess. So things that are alike are perceived together. So if you're similar, you could be similar in shape, similar in size, color or hue is another name for it, orientation, brightness. and lightness and i think i have oh i thought i had a different one there but um so so if you look at these two pictures um are you seeing columns or are you seeing rows i think among the blue set of images, you probably see columns.
In contrast, when you look at the set of red objects, you probably see rows. Now, there's no reason for that. There's no logical, objective reason for thinking that. A computer might not know whether to see rows or columns in those objects.
It would have to figure it out. It would have to set up a system, in fact, to to a series of decision-making principles to decide whether something was a row or something was a column we automatically just tend to see either rows or columns based on this similarity principle continuity is another interesting one um so in this lower picture uh in the like the middle left picture we have a blue line a circle and another blue line Is that three separate objects? Is it a line, a circle and a line that just happen to be touching each other?
Is it one continuous line with a circle in front? Is it a half of Harry Potter's glasses? You know, so that's another image we could see. But so the continuity principle tends to be the case that we tend to sort of impose or assume, you know, automatically connectivity or continuity to make a more simple.
understanding of the objects. So lines and patterns tend to be perceived as continuing in time or space. There's a circle behind a pole and a pole or a bar in front.
But in fact, it doesn't have to be that way. We could be looking at, you know, two funny shapes, you know, two partial circles with a flat bottom and the line extends. But we don't tend to see that.
Similarly, the image on the right where you have these slanted lines and vertical lines, we tend to assume that there's a continuous straight line behind an angled bar in front. We're seeing some degree of depth perception because of continuity, but objectively speaking that's not necessarily the case. Another aspect of this principle is the law of good continuation.
Points when connected result in straight or curving lines. So when we look to the right, we have black circles and red circles. And I think many of us would, even though there's black circles and red circles, we tend to see a vertical line and a curvy line rather than sort of weirdly shaped red sort of curvy lines and black. curvy lines. You can, like we have the ability to flip in this case, but we tend to automatically look at continuation or continuity rather than similarity of color in this case.
But sometimes there is competition between the different principles. And this last one is the Gestalt principle of common fate. Objects moving together will be psychologically or perceptually grouped.
together. So this is a picture of a group of birds and instead of seeing each one as an independent object, we tend to see and they're all flying and it appears as if they're moving together, as if they belong together. And then I think I have three demonstration videos for you where it shows different examples of this common fate principle. How you will see, you know, automatically in your mind group objects that just happen to be moving together.
even though technically they're not necessarily a group. We just see it that way. If you have any questions, please let me know. Post them on the general discussion board, then everybody can see them and I can answer and everybody can hear my answer.
Anyway, I'll talk to you again and maybe see you during one of the Q&A sessions. Thanks.