apsych c7--perception

what is perception?

• perception is the process of understanding and interpreting sensations

the absolute threshold of perception is the smallest amount of a stimuli we can detect (for example, what is the smallest thing you can see)

• the difference threshold/just noticeable difference is the smallest amount of change in that stimuli for us to notice the change

  • formed by weber’s law (the change needed is proportional to the original intensity of a stimuli, so if you put a bunch of hot sauce in an already hot dish, you won’t see a difference, but you would if there was none there to begin with)

  • each sense has a different percentage for how much change you would need to notice a difference

perceptual theories

• signal detection theory: looking at the effects of distractions and interferences we experience during perception

  • what determines what we perceive is called response criteria. i like bananas, so if i am hungry, i might smell them more than someone who doesn’t like bananas

  • false positive—seeing something not there

  • false negative—not seeing something there

• top-down processing: fill in gaps by what we sense because we use background knowledge

  • this creates schemata, which is our mental representation of how we expect the world to be. it creates perceptual sets, which is seeing something in a certain way because of your experiences

    • seeing animals in the clouds

• bottom-up processing/feature analysis: the reverse of bottom up, we use the features of the object itself to build a compete perception.

  • reading a book for the first time and focusing on each word instead of finishing the sentence in your head

principles of visual perception

• figure-ground relationship: debating what is the background and what is the picture in something, aka “optical illusions”

• gestalt psychology/gestalt rules: we normally see images as groups and not isolated elements (chart pg 62, but just remember the terms proximity, similarity, continuity, and closure)

• constancy: being able to maintain a constant perception of an object despite the changes in our vision, light, etc. every moment! chart pg 63

• perceived motion: our ability to gauge motion is key, although sometimes we think things are moving that are in fact not

• depth cues: we need to know depth!

  • visual cliff experiment: experiment which put infant on one side of a glass-topped table which creates impression of a cliff, shows how we have depth perception

  • monocular depth cues are depth cues that do not depend on having two eyes, binocular need two eyes

monocular cues (look up example pics):

• linear perspective

• relative size cue

• interposition cue (objects that block our view of other objects must be closer)

• texture gradient (details are visible close by but not far)

binocular cues:

• retinal disparity, or binocular disparity, is when our brain receives an image from both eyes. an image far away will mean both eyes see a similar image, close is vice versa.

• convergence: objects get closer to us, eyes move toward eye other, our brain knows because of this that an object is close or far

effects of culture on perception: we can learn stuff from our cultures that determine how we see things