Sensation and Perception (week 9)

gustatory system

frontal lobe

kinestetic system

Parietal lobe

Perception

* psycological process
* signals that reach brain: selected, organized and interpreted

Sensation

* physiological process
* taking in raw physical energy

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Physiological effect

The effect a sensation has on the body

proximal stimulus

In perception, it is the information our sensory receptors receive about the object.

Transduction

conversion of raw physical energy into sensory neurological signals

process of sensation--transduction--perception

stimulus energy--sensoty receptiors--neural impulses--brain

Interpretation

The brain guessing what kind of distal stimulation created that pattern of sensory (proximal) stimulation

distal stimulus

In perception, it is the actual object or event out there in the world, as opposed to its perceived image.

nervous system

the network of nerve cells and fibers that transmits nerve impulses between parts of the body.

Neuron

a nerve cell, the basic building block of the nervous system

Neuron cell body

location of the nucleus with DNA

Dendrites

Branchlike parts of a neuron that are specialized to receive information.

Axons

a part of a neuron that carries impulses away from the cell body

axon terminal

The endpoint of a neuron where neurotransmitters are stored

Diameter of an axon

Determines communication speed in both vertebrates and invertebrates

Myelin

A layer of fatty tissue segmentally encasing the fibers of many neurons in vertebrates, enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

Nodes of Ranvier

gaps in the myelin sheath

Lack of myelin

Significantly impairs motor and cognitive function (eg. Multiple sclerosis)

Resting potential

-70 mV, the state of the neuron when not firing a neural impulse

Axon membrane

has chemical gates that can open to allow electrically charged particles to enter or can close to keep out electrically charged particles

Transferring information between neurons

1. Electrical charge travels down axon to axon terminal
2. Synaptic vesicles release neurotransmitters into synaptic gap
3. Neurotransmitters are picked up by dendrites of receiver neuron

synaptic vesicles

Membrane-bounded compartments in which synthesized neurotransmitters are kept.

Inhibitory neurotransmitters

chemicals released from the terminal buttons of a neuron that inhibit the next neuron from firing

Psychophysics

the study of how a physical stimulus is converted into perceptions

Absolute threshold

the minimum stimulation needed to trigger response

high threshold

low sensitivity to stimulus (more stimulation needed for the observer to detect it)

low threshold

high sensitivity to stimulus (less stimulation needed for the observer to detect it)

Crossover point

the point at which a person changes from detecting to not detecting a stimulus or vice versa

stimulus intensity

how strong a stimulus needs to be to be detected

JND (just notable Diffferences) threshold

smallest amount of stimulus to trigger noticable psychological perception

Signal detection theory

emphasises various factors and influences that can affect detection of stimuli

(explains why we regognize some signals and ignore others when faced with multiple stimuli)

Response criteria

how motivated we are to detect certain stimuli and what we expect to perceive

liberal response bias

high hit rate, high false alarm rate

- will readily report that the signal is present in ambiguous situations. These participants typically produce more hits and false alarms

sensory sensitivity

the extent to which a person registers sensory information. Measured by the difference of hits and false alarms

sensory adaptation

when sensitivity to stimuli gradually weakens due to increased/extended exposure to stimuli

subliminal perception

Acetylcholine

Excitatory neurotransmitter that causes muscle contractions. Black widow venom releases mass amounts of it, causing muscle spasms. Without acetylcholine, a person can be paralyzed

Curare

Blocks uptake of acetylcholine and causes paralysis. Used in stun darts

Glutamate

Common excitatory neurotransmitter in the brain

GABA

Inhibitory neurotransmitter. Sleeping pills increase the receptor’s access to GABA

Light

a form of electromagnetic radiation that is visible to the eye

Newton's view on light

Light is particles, called photons

Maxwell's view on light

Light is a wave created in the electromagnetic continuum

Amplitude of light

determines brightness

Wavelength of light

determines color (longer waves appear more red)

Cornea

the transparent layer forming the front of the eye.

Functions of the cornea

- responsible for refraction of light entering the eyes
- performs coarse focusing of light rays
- Keeps fluid inside of eye
- Protects eye from outside harm

Corneal disease

occurs when the cornea, the front surface of the eye, becomes clouded, scarred, or distorted by injury, disease, or hereditary defects. Creates a rainbow/halo effect around objects

corneal transplant

replacement of damaged cornea with donated tissue

Astigmatism

a condition in which the eye does not focus properly because of uneven curvatures of the cornea. Makes certain orientations of lines difficult to focus

Iris

a ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening

Pupil

the adjustable opening in the center of the eye through which light enters

Pupil and arousal

Pupil size can be controlled by autonomic nervous system. Adrenaline can cause pupils to dilate (eg. attraction- people find dilated pupils more attractive)

senile miosis

Normal with age
Restriction of light entering the eye
Decrease in *resting diameter* of the pupil
Makes it harder to see in low light

Albinism

Absence of pigment in the skin, hair, and eyes. Eyes appear red because of reflection of blood vessels. Can create vision problems by clear irises not keeping light out

Lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

Ciliary muscles

muscles which relax or contract and alter the shape of the lens. Bulge the lens for close objects and flatten for far away objects

Myopia

nearsightedness

Axial myopia

myopia in which the eyeball is too long. light rays from far objects converge in the front of the eye, making them appear out of focus

Refractive myopia

myopia (nearsightedness) in which the cornea and/or the lens bends the light too much

Hyperopia

A condition in which visual images come to a focus behind the retina of the eye and vision is better for distant than for near objects -- called also farsightedness.

axial hyperopia

eyeball is too short. light from objects focuses behind the retina

Refractive hyperopia

cornea/lens bends too little light

presbyopia

farsightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.

Anomalies in colour vision with age

It gets harder to distinguish colours in the blue/green end of spectrum

Cataracts

Lens becomes milky-coloured which makes it hard to see through. Can be fixed through replacement with artificial lens

what are the 5 sensory systems

* visual
* auditory
* olfactory
* gustatory
* kinesthetic

visual system

occipital lobe

auditory system

temporal lobe

olfactory system

temporal lobe