Unit 3 Principles of Perception

Principles of Perception 1. Figure-Ground When looking at an image, the “figure” is the main object of focus, and the “ground” is the background that it is set against. 26 The same stimulus can be identified as more than one thing if you shift your focus of what is figure and what is ground. 27 Principles of Perception 2. There are rules of GROUPING that our mind uses to sort the stimuli: – Proximity – Similarity – Continuity / Continuation – Connectedness – Closure – Symmetry – Simplicity / Prägnanz 28 GROUPING - Proximity • Things that are near each other get grouped together (and separately from what’s not close) Here we see Here we see one 6x6 square 3 sets of 2 columns 29 GROUPING - Similarity Items that are similar tend to be grouped together. People see vertical columns of circles and squares Rather than rows of square – circle – square – circle, etc. 30 GROUPING – Continuity / Continuation • We tend to see continuous lines or shapes. • If something disrupts a picture, we see through the object to see one continuous whole, rather than separate pieces. 31 GROUPING - Connectedness • Things that are connected are more related than things that aren’t connected. Two squares & two circles Two units of a circle and a square 32 GROUPING - Closure • We fill in information, in order to make a single, recognizable pattern. We close the gaps. 33 GROUPING – Symmetry • Forms that together create symmetry are grouped together 34 GROUPING – Simplicity Law of Prägnanz • We tend to recognize things that are simple and clear, rather than complex and awkward. We see shapes rather than a bunch of lines. The Law of Prägnanz explains why we use grouping principles. 35 Principles of Perception 3. CONSTANCY • SHAPE constancy – the perception of a shape remains constant even though the retinal image changes 36 CONSTANCY • SIZE constancy – the perception of size remains constant even as distance changes – We know a car is still the size of a car, even though it appears tiny from far away. – One of the reasons why we maintain size constancy is because even though the image is getting smaller, so is everything else. The proportions remain constant. 37 Ponzo Illusion – Experience tells us that if an object farther away appears to be the same size, it must be because it’s bigger. If contextual clues imply distance, the “farther” one will be perceived as bigger. 38 Ebbinghaus Illusion 39 Muller – Lyer Illusion 40 Ames Illusion • A room is in the shape of a trapezoid – one corner is farther back than the other. • The wall of the farther corner is also higher than the wall of the closer corner. • When viewed through a peephole, the room appears rectangular. • The person standing in the far corner appears much smaller than the person standing in the near corner. 41 42 4. DEPTH PERCEPTION • Depth perception is our ability to see objects or scenes in 3 dimensions: up/down, left/right, front/back (2 dimensions is just up/down, left/right) • We get depth perception from binocular vision (cues) – the combined visual information from both eyes • Our eyes are about 2.5 inches apart, so they see slightly different images - retinal disparity 43 Visual Cliff-demonstrates learned depth perception 44 5. DISTANCE PERCEPTION • Distance perception is our ability to judge distance • We get distance perception from monocular cues – information we get from either eye (both eyes may see the information, but we would get the same perception / cues even if only one eye was looking) • (Distance perception helps us judge distance even if depth perception is missing.) 45 Monocular Cues • Relative size-if similar size, smaller one is farther away • Relative height-higher in our visual field must be farther away • Linear perspective-parallel lines appear to come together as they get farther away • Interposition- if one item is blocking another that one is closer • Light and shadow-nearby objects reflect more light, the dimmer object is farther away • Relative motion/motion parallax-as we move, items that are stable look like their moving 46 Motion Perception Images closer than the fixation point move in opposite direction. Images beyond the fixation point move in the same direction. Closer images appear to move more quickly. 47 Phi Phenomenon The phi phenomenon is the optical illusion of perceiving a series of still images, when viewed in rapid succession, as continuous motion. Ex. flashing word signs