Sensing the Environment

describe the visual pathway

• light enters the eye through cornea and passes through the aqueous humor

• light hits the photoreceptors within the rod and cone cells of the retina

• stimulated rods and cones transmit a signal that passes through the retinal cells to the optic nerve

• the optic nerve ends at the lateral geniculate nucleus and relays information to the occipital lobe

what controls the amount of light let into the eye?

• iris

• sphincter muscles close the pupil (less light in)

• contraction of dilator muscles let more light in as they relax

parvocellular cells are responsible for ___ that allow for detailed image detection

high spatial resolution

optic chiasm

• where signals from the nasal retina crossover (conveys information form the temporal visual fields)

fovea

• area of the eye with only cones (no rods)

• central part of the macula

rods

• make up a majority of the photoceptor cells in the eye

• visual pigment = rhodopsin

• primarily contribute to scotopic vision

  • vision at night

top-down processing

• immediate recognition based on prior experience and context

• ability to perceive objects that aren’t/are partially there

interposition

• when one object covers or obscures another, the object that covers the other is closer

motion parallax

• closer objects appear to move faster than distant objects

proprioception

• the sense of balance that allows people to be aware of the body’s positions

• change in movememnent

mechanoreception

• detects stimuli like pressure and vibration

• touch and sound

nocioreception

somatosensory perception of pain

somatosensation

• overall term for the detection and interpretation of stimuli

• touch

farsightedness

• hyperopia

• eye is too short

• lens cannot bend light enough

• only see far away objects

nearsightedness

• eye is too long

• lens bends light too much

• only sees objects closeby

retina

• has photoreceptors that receive lights

  • cones (full-color range)

    • in the center region of retina

  • rods (grey-scale image, cover most of retina)

    • in the perimeter of the retina

phototransduction

• process by which rods and cones convert photons into electrical signals in the reina

• occur b/c opsins (pigments)

left visual field projects onto the ___ side of the rina

right

right visual field projects onto the __ side of the retina

left

spatial resolution

• the ability to distinguish differences in the smaller details of an object

temporal rosulution

• refers to how quickly the visual information is changing in our visual field

parvocellular cells

• in thalamus

• LGN

• high spatial resolution of stationary objects

magnocellular cells

• moving objects

• high temporal resolution (shape and color)

• no fine details

• in LGN

parallel processing

• humans interpret visual information simultaneously

olfactory chemoreceptors

• nerves that detect the aroma of a given molecule

• located in the upper part of the nasal cavity

• stimuli binds to chemoreceptors causing a chemical signal

pheromones

chemicals secreted by one animal which elicit a response from another animal of the same species

taste pathway

• information travels from taste buds (has chemoreceptors) —> brain stem —> thalamus

• The thalamus passes signals to the frontal lobe and flavors are determined

somatosensory system includes

• skin

• mucous membranes

• limbs

• joints

perception

being aware of the world around you, integrated information

sensation

process of obtaining raw sensory information

bottom up processing

• the usage of real-time visual stimuli to perceive an image

• no prior knowledge of stimuli

face pareidolia

• seeing facing in things that are not there

depth perception

• relies on visual cues to determine their distance

relative size

objects appear larger the closer they are

constancy

• we perceive characteristics of an object to remain the same despite changes in the stimuli and environment

gestalt principles

• our tendency to perceive and interpret certain configurations at the level of the simpler whole

law of proximity

• we perceive objects closer together as a group

law of similarity

our tendency to group similar objects together

law of continuation

our tendency to perceive “good” continuous patterns

subjective contours

perceiving contours that are not really there

law of closure

• our brains fill in the missing parts for an image and we perceive it as a whole

which muscles in the retina focus light?

• ciliary muscles

• change the shape of the lens

signals in the somatic sensory system are sent where in the brain?

• somatosensory cortex

  • parietal lobe