INTRODUCTION TO PSYCHOLOGY 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 – When blind people can sense and describe things they can’t see.

Perceiving Images The first step in perceiving an image is determining the figure and ground. People walking v. arrows going up and down Man’s face v. liar written in cursive

Do you see the arrow?

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

Perception “Perception refers to the interpretation of what we take in through our senses. In terms of optical illusions this means our eyes.” Simply put, our brains are tricked into seeing something which may or may not be real. http://www.keele.ac.uk/depts/aa/widening/uniworld/webclub/rs/optical.htm

Motion Perception How does the brain recognize an object is moving 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

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.

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. http://www.youtube.com/watch?v=-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 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? Baseball Softball Small salad plate Large dinner plate Frisbee Basketball Beach Ball BB Pea Dime Penny Nickel Quarter Golf ball