PERCEPTION Our ________________ of the stimuli coming in from the world around us

Stimuli are processed in two ways: 1. Bottom-up processing: 1. Bottom-up processing: –focuses on the raw material that enters through our sensory systems 2. Top-down processing: 2. Top-down processing: – focuses on how our expectations and experiences influence our interpretation of incoming stimuli

ORGANIZATIONAL PRINCIPLES Gestalt Psychologists: These psychologists emphasize our tendency to integrate pieces of information into meaningful wholes These psychologists emphasize our tendency to integrate pieces of information into meaningful wholes -Focusing on individual stimuli misses the point and that humans tend to perceive things in meaningful units (we group stimuli). x

Form Perception Figure and Ground: Figure and Ground: - Our perceptual processes actively try to assign some stimuli to the foreground (figure) and some to the meaningless background (ground). -The figure is the prominent object (or sound, tastes, etc.) and the ground consists of everything else surrounding the figure (the background)

Prince Phillip and Queen Elizabeth The principle of figure and ground. This is also known as an ambiguous figure (can be interpreted as 2 or more images)

A more updated version of figure/ground by Olly Moss

ORGANIZATION PRINCIPLES Grouping – The perceptual tendency to organize stimuli into groups that we understand. Rules for grouping stimuli together Rules for grouping stimuli together - proximity - similarity - continuity - connectedness - closure

PROXIMITY The tendency to group items that are near one another The tendency to group items that are near one another –Basketball players sitting on the bench must be members of the same team

SIMILARITY Our tendency to group items that appear to be the same Our tendency to group items that appear to be the same –People wearing the same uniforms must be a team

CONTINUITY The tendency to assume that apparent movement will continue in the way that it started (a dish of spaghetti has lots of long strands with hidden parts; it is not a pile of short pieces) The tendency to assume that apparent movement will continue in the way that it started (a dish of spaghetti has lots of long strands with hidden parts; it is not a pile of short pieces) Figure 4.26: Gestalt principles of perceptual organization. (e) Continuity: You tend to group these dots in a way that produces a smooth path rather than an abrupt shift in direction.

CONNECTEDNESS Because they are uniform and linked, we perceive each set of two dots and the line between them as a single unit Because they are uniform and linked, we perceive each set of two dots and the line between them as a single unit

CLOSURE The tendency to close gaps and perceive images as a whole, not a collection of parts The tendency to close gaps and perceive images as a whole, not a collection of parts

Depth Perception Depth Perception: ability to see objects in three dimensions even though the images that strike the retina are two dimensional. Depth Perception: ability to see objects in three dimensions even though the images that strike the retina are two dimensional. –Allows us to judge distance.

DEPTH PERCEPTION Ability to judge distance and see the world in three- dimensions. Ability to judge distance and see the world in three- dimensions. Biological maturation predisposes our wariness of heights, and experience amplifies it (nature and nurture). Biological maturation predisposes our wariness of heights, and experience amplifies it (nature and nurture). be.com/watch?v=p 6cqNhHrMJA be.com/watch?v=p 6cqNhHrMJA be.com/watch?v=p 6cqNhHrMJA be.com/watch?v=p 6cqNhHrMJA

How do we transform two-dimensional objects to three-dimensional perception? Binocular cues – depth clues from both eyes together Binocular cues – depth clues from both eyes together –retinal disparity –convergence Monocular cues – depth clues from a single eye Monocular cues – depth clues from a single eye –motion parallax –accommodation –pictorial depth cues

BINOCULAR CUES Retinal/binocular disparity: Retinal/binocular disparity: –The difference between the two images that the brain is receiving in the visual cortex. –Objects within 25 feet project images to slightly different locations on the left and right retinas; thus each eye sees a slightly different view of the object. –The closer an object comes to you, the greater the disparity is between the two images. See retinal disparity in action with the “finger sausage” illusion See retinal disparity in action with the “finger sausage” illusion Now try bringing the points of 2 pencils together about 12 inches in front of your face with one eye closed. Depth perception does benefit from binocular disparity! Now try bringing the points of 2 pencils together about 12 inches in front of your face with one eye closed. Depth perception does benefit from binocular disparity! Convergence: Convergence: –The amount of tension in the eye muscles increases as an object gets closer. –You feel the eyes converge toward each other as they focus on a target. Tricks we use to see depth with BOTH eyes. So if you are missing an eye, these will do you no good.

MONOCULAR CUES Relative height Relative height Relative size Relative size Relative motion Relative motion Interposition Interposition Relative brightness (light and shadow) Relative brightness (light and shadow) Accommodation Accommodation Linear perspective Linear perspective Texture gradient Texture gradient Relative clarity Relative clarity Monocular cues are tricks that we (and artists who draw a lot) use to judge depth perception. Monocular cues are tricks that we (and artists who draw a lot) use to judge depth perception. What makes them monocular cues is that you need only one eye to use them. What makes them monocular cues is that you need only one eye to use them.

Relative height – We perceive objects higher in our field of vision as farther away. Relative height – We perceive objects higher in our field of vision as farther away. Relative Size – If we assume two objects are similar in size, most people perceive the one that casts the smaller retinal image as farther away. Relative Size – If we assume two objects are similar in size, most people perceive the one that casts the smaller retinal image as farther away. Relative Motion (Motion parallax) – A difference in the apparent rate of movement of different objects provides information on the relative distance of those objects. Relative Motion (Motion parallax) – A difference in the apparent rate of movement of different objects provides information on the relative distance of those objects. – As we move, objects that are actually stable may appear to move. While riding on a bus you fix your gaze on some object – say, a house – the objects beyond the fixation point appear to move with you; objects in front of the fixation point appear to move backward. The farther they are from the fixation point, the faster they seem to move. MONOCULAR CUES cont.

Depth Cue Relative Size Instructor’s Notes Copyright © Houghton Mifflin Company. All rights reserved. PowerPoint® 2000 or better with Flash® plug-in required to view animations. Right-click on animation for playback controls.

MONOCULAR CUES cont. Interposition – If one object partially blocks our view of another, we perceive it as closer. Interposition – If one object partially blocks our view of another, we perceive it as closer. Relative Brightness (Light and shadow) Relative Brightness (Light and shadow) –Nearby objects reflect more light to our eyes. Thus, given two identical objects, the dimmer one seems farther away. –Shading, too, produces a sense of depth consistent with our assumption that light comes from above. Invert the picture to the right and the hole in the ground becomes a hill. Accommodation – Changing the shape of the lens to focus near or far objects on the retina. Effective only for objects within 25 feet. Accommodation – Changing the shape of the lens to focus near or far objects on the retina. Effective only for objects within 25 feet.

Depth Cue Interposition Instructor’s Notes Copyright © Houghton Mifflin Company. All rights reserved. PowerPoint® 2000 or better with Flash® plug-in required to view animations. Right-click on animation for playback controls.

Depth Cue Shadowing Instructor’s Notes Copyright © Houghton Mifflin Company. All rights reserved. PowerPoint® 2000 or better with Flash® plug-in required to view animations. Right-click on animation for playback controls.

Linear perspective – Parallel lines, such as railroad tracks, appear to converge with distance. The more they converge, the greater their perceived distance. Linear perspective – Parallel lines, such as railroad tracks, appear to converge with distance. The more they converge, the greater their perceived distance. Texture Gradient – Refers to the amount of detail that can be seen. The coarser (more textured) it looks, the closer it is Texture Gradient – Refers to the amount of detail that can be seen. The coarser (more textured) it looks, the closer it is Relative Clarity – Basically the same concept of texture gradient. We assume hazy objects are farther away. Relative Clarity – Basically the same concept of texture gradient. We assume hazy objects are farther away. MONOCULAR CUES cont.

Depth Cue Linear Perspective Instructor’s Notes Copyright © Houghton Mifflin Company. All rights reserved. PowerPoint® 2000 or better with Flash® plug-in required to view animations. Right-click on animation for playback controls.

Depth Cue Text Gradient Instructor’s Notes Copyright © Houghton Mifflin Company. All rights reserved. PowerPoint® 2000 or better with Flash® plug-in required to view animations. Right-click on animation for playback controls.

Depth Cue Relative Clarity Instructor’s Notes Copyright © Houghton Mifflin Company. All rights reserved. PowerPoint® 2000 or better with Flash® plug-in required to view animations. Right-click on animation for playback controls.