Perception How we organize and interpret sensory information

Selective Attention Video Card trick Basketball game

Selective attention - we can only focus awareness on a limited part of what we are sensing. Cocktail party effect – type of selective attention in which you can attend to only one voice at a time Cell phones and driving? Listening to music and studying?

Visual Capture The tendency for vision to dominate your senses. At an IMAX movie, it feels like you are moving because it looks like you are moving. Your vision dominates over your vestibular system.

Parallel processing – processing many things at once Man who mistook his wife for a hat – could see form but not the big picture Colorblindness with functional cones Motion blindness Blindsight

Perceiving Images The first step in perceiving an image is determining the figure and ground.

Do you see the arrow?

Gestalt and the Urge to Organize

Other gestalt principles Simplicity

Gestalt Principles: Closure

Gestalt Principles: Continuity

Gestalt Principles: Proximity

Gestalt Principles: Similarity

Gestalt and the Lion King

Motion Perception How does the brain recognize an object is moving? How does it interpret the direction of movement ? Brain interprets shrinking objects as receding and enlarging objects as approaching

Stroboscopic Effect the perception of motion produced by a rapid succession of slightly varying images (animation, movies) Stroboscopic effect Stroboscopic effect

Phi phenomenon an illusion created when two or more adjacent lights blink on and off in succession, creating the perception of movement (lighted signs, illusions)

Perceptual Constancy the ability to perceive an object is the same even as the illumination and retinal image changes. Shape Constancy- perception that shape of an object doesn’t change just because image on the retina does.

How many right angles do you see?

Perceptual Constancy Size constancy (King Koch or the incredibly shrinking teacher) – perception that an object’s size remain the same even as the retinal image changes.

Perceptual Constancy Color Constancy – the perception that familiar objects have a consistent color, even if changing illuminations alter the wavelength reflected.

Perceptual Constancy Lightness constancy – the perception that familiar objects have a constant lightness, even while illumination varies.

Visual Cliff – used to check for depth perception.

Pre-Renaissance Art The Holy Innocents by Giotto di Bondone.Giotto di Bondone Jesus on Way to Calvary Simone Martini Simone Martini

Masaccio, Trinity (ca. 1425). Leonardo Da Vinci, The Last Supper Renaissance Art

Depth Perception Monocular Depth Cues  Linear perspective (parallel lines appears to converge on a vanishing point)  Relative height (more distant objects are higher)  Relative size (more distant objects are smaller)

Depth Perception Monocular Depth Cues  Relative clarity (objects in the distance appear hazy)  Overlap/interposition (continuous outlines appear closer)

Depth Perception Monocular Depth Cues  Texture gradient (texture details, like roughness, diminish with distance )

Depth Perception Monocular Depth Cues  Light and shadow

How many can you identify here?

Depth Perception Monocular Depth Cue  Motion parallax (or relative motion) – Distant objects will appear slow in comparison with close objects even when the two are moving at the same speed  Think of an airplane traveling overhead.  OmK3rGk__I&NR=1 OmK3rGk__I&NR=1

Depth Perception Binocular depth cues – require two eyes  Retinal disparity – the greater the difference between the images on your two retina, the closer the object (“camera 1, camera 2”, “finger sausage”, hole in the hand)  Convergence – the greater your eye muscles must strain (or converge) to focus on an object, the closer the object (notice how hard your eyes strain when you focus on the tip of your nose).

Size-distance relationship When other monocular cues tell us an image is further away, it actually appears larger.

Horizon Moon

High moon on a clear night.

Horizon moon Which object would you need to hold at arms length to just cover the moon? BB Pea Dime Penny Nickel Quarter Golf ball Baseball Softball Small salad plate Large dinner plate Frisbee Basketball Beach Ball

High moon on a clear night. Which object would you need to hold at arms length to just cover the moon? BB Pea Dime Penny Nickel Quarter Golf ball Baseball Softball Small salad plate Large dinner plate Frisbee Basketball Beach Ball

Muller-Lyon Illusion Which is longer?

Muller-Lyon Illusion

Perceptual Adaptation

Perceptual Set

TIME FLIES I CANT THEYRE TOO FAST MacDonald MacHenry MacDuff Machinery FOLK CROAKSOAK

Context Effects

I/O Psychology – Human Factors I/O Psychology – Industrial/Organizational psychology Human factors – a branch of psychology that explores how people and machines interact to create machines that are more efficient and safer

Extrasensory Perception Telepathy – mind reading Clairvoyance – perceiving remote events Precognition – Knowing things before they happen Telekinesis (psychokinesis) – moving objects with one’s mind (not technically ESP)