Perception Unit 4

Form perception Perception is taking sensory input and giving it meaning. Gestalt… …whole sum is greater than the parts. Ex.: 3 pac-man shapes arranged appear as a triangle. Figure-ground – situation where we see either a figure-against-a- background, OR the background becomes the figure. Ex.: the vase/profile of people

Cont. Grouping – we lump similar things together. Here’s how… Proximity Similarity Continuity Closure Connectedness

Depth perception = the ability to gauge distance. Visual cliff – babies will not crawl across a glass table; they can perceive depth. Binocular cues – our eyes are 2 ½ inches apart. We see from 2 angles. (finger sausage) Retinal disparity enables our brain to calculate distances.

Depth (cont.) Monocular cues – these are good for long distances. Relative height – higher up  farther Relative size – bigger  closer Interposition – stacked items Linear perspective – think RR tracks Light & shadow – dark  close; light  far Relative motion – fast moving  close; slow  far Texture gradient – detailed  close

Big = close Small = far

Taller or wider?

Light

Depth… Size? Shading? Texture? Linear perspective?

Motion perception & Constancy Stroboscopic effect – series of still pics shows motion (old films) Phi phenomenon – 2 lights flashing seems like movement back/forth Shape constancy – tendency to expect things hold their shape Lightness constancy – tendency to expect light to remain the same. Color constancy – tendency to expect color to remain the same.

Constancy (cont.) Size constancy – tendency to expect things to retain their size Moon illusion – moon low on horizon looks huge due to trees/houses Muller-Lyer illusion – two equal lines appear different lengths Ponzo illusion – linear perspective makes “distant” items look big Ames room – funky-shaped room fools our expectations about a room.

Funky dog house (expectations matter)

Misc. Perceptual adaptation = our ability to adjust to changes in our sensations. Ex.: “inversion goggles” (that skew/flip vision)…our brain corrects them Perceptual set = what we’ve already experienced & thus expect. Ex.: a log floating on Loch Ness is the monster! Context matters. We expect things to be in context/normal. Ex.: “It’s wagging its tail, what a cute little log.” (we might hear “dog”) Ex.: curious rabbits climbing in boxes (either on floor or from ceiling) Ex.: a 6’9” basketball player seems small beside a 7’9” player

Expectations…

Misc. (cont.) Emotions & motivations matter Hiking up to a hill. If tired, it looks huge. If refreshed, not so big. If motivated to see something, people likely do. Seen in the horse/seal ambiguous image. ESP = extra sensory perception Idea some people can sense things beyond normal senses ½ of people believe it’s real “Psychics” seem really good at manipulating/leading people along Science says, nah