psych101 chapter 4: Sensation and Perception

sensation

way in which we represent energy from word in our nervous system

perception

organization and interpretation of sensory info, happens below conscious awareness

Bottom up processing

eyes collect visual info, we organize and interpret, then perceptions are made. SIMPLEST of stimuli to complex

Top down processing

perceiving something first, then checking, then recognizing. Building on ideas of the world and looking for what confirms it.

Proprioception

perception of where body is in space

Transduction

transforms stimuli into neural impulses, the main part of sensation. Delivers neural info to the brain

Psychophysics

relationship with physical energies and psychological experiences

signal detection theory: how and when will we detect a faint stimulus? (feeling something you don’t see)

Priming

unconscious activation from sensory stimulus

subliminal sensation

something that came and went so fast to perceive

subliminal persuasion

theory that subliminal stimuli and sensation can change or influence behaviour

sensory adaptation

becoming less sensitive to constant stimuli. It tunes the signal to noise ratio; increasing focus by decreasing background noise.

Perceptual set

predisposition to see one way and not the other way

Schemas

organization of info in our brain and how we interpret it

ex. how do you perceive a dog generally? you may see it as floppy eared, brown eyes, brown fur, etc. even though all kinds of dogs are different

context effects

cultural experiences heavily influence how we see the world

motives

seeing the world the way we want to

emotions

how we feel influences world around us

wavelength

how long a lightwave is

hue

color

intensity

how bright or dim the light is

frequency

the number of complete wave cycles that occur in a given unit of time

amplitude

how bright or dim something is

retina

The light-sensitive layers of nerve tissue at the back of the eye that receive images and sends them as electric signals through the optic nerve to the brain.

accommodation

the eye's ability to change its focus from distant to near objects by altering the shape of the lens.

cornea

the transparent layer forming the front of the eye.

Photoreceptor cells

rods and cones

rods

we have lots of rods, around 120 million. They are long and rod-like and are sensitive to light

cones

not a lot of cones, around 7 million. They are stumpy and sensitive to detail and color. We have 3 different types of cones that are all sensitive to different wavelengths

Vision

visual and info processing, organization of sensory info. Everything is flipped, seeing something from the right side gets processed on the left retina, receiving info from the right side of the world goes to the left hemisphere (contralateral)

Helmholtz and color

every color seen with the human eyes canbe created with red, green and blue (relates to the different cones) 

Trichromatic color theory

guesses that if we can see all colors from 3 colors, then we should have 3 types of color-sensing cells

Opponent signal theory

competition between signals

ex. afterimages, where staring at a color for a long time fatigues the corresponding photoreceptors. When you look away, the opponent channel overcompensates, making you see the opposite color. 

feature detection

neurons in brain are responding certain features of the stimulus is- processing shape, color, texture, etc, individually and then putting them all together to create a picture

serial protection

processing things one at a time, like a computer

Dorsal pathway

the “where” pathway- has to do with movement, space, and depth

Ventral pathway

the “what” pathway- has to do with shape, form, color, and object

gestalts

an organized whole that is perceived as more than the sum of its parts.

grouping

tendency to organize stimuli into groups

figure-ground

we organize the world based on objects that stand out

depth perception

ability to see objects in 3D, allowing us to judge distance. Top down perception helps us understand small things are far away

retinal disparity

the different perspectives of images perceived by the left and right eye

binocular cues

two eyes have 2 different images and these images create a 3D world

monoculare cues

depth cue only with one eye

Phi phenomenon

when you present still images in rapid succession so it looks like it’s moving- lead to the creation of film

color constancy

Color is a psychological phenomenon, a top-down process. 

ex, the knowledge that a banana is always yellow

size consistency

we don’t see people or objects shrinking and growing, just getting farther and closer

relative luminance

understanding brightness due to context

Perceptual adaptation

ability to adjust sensory input

Transduction

converting one energy to another

ex. sound waves pass eardrum, causing wobbling, moves to the cochlea which has fluid and hair that causes rippling, sending signals to the temporal lobe and auditory cortext

Intensity of common sounds

hearing is naturally sensitive, but we expose ourselves to loud noise, leading to damage of hair cells, preventing transduction. We lose hearing of higher frequencies first

Cochlea place theory

Apex is wide and flexible and hears low sounds, base of cochlea hears higher pitches

Frequency theory

measured w/ action potential per second/ The lower the AP, lower the frequency and the higher the AP, the higher the frequency

Sound shadow

when frequencies are being blocked by media (walls, floor, own body) and it creates an area of silence (like covering ears when child screams). Higher frequencies are easier to block, while lower frequencies are better at travelling through the media

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