Sensation and perception

• Sensation: The study of how our senses first detect incoming stimuli and process it through the brain and nervous system

  • Bottom-up processing: How sensation works

• Perception: The process of (our brain’s) organizing and interpreting raw sensory data and creating meaningful patterns

  • Top-down processing: How perception works

• Absolute threshold: Weakest level of a stimulus that can be accurately detected at least 50% of the time (applies to all senses)

• Signal detection theory: Helps us understand how quickly we can notice and interpret incoming stimuli

• Difference threshold (just noticable difference): The smallest detectable change in a stimulus

  • Ex: how much does the volume have to increase before you can tell it has gotten louder?

• Sensory adaptation: The diminishing of sensitivity to an unchanging stimulus

  • Ex: cold water in a swimming pool. At first the water seems frigid, but if you stay in for a while, you’ll “get used to it”

• Parallel processing: The processing of several elements of a problem simultaneously.

  • Ex: the brain breaks vision into separate dimensions such as color, depth, movement, & form

• Subliminal stimulation

  • Every individual has their own absolute threshold

  • Temporarily affects short-term thinking.

• Transduction

  • Applies to all the senses

  • The process in which sensory information is converted into neural energy/messages.

• Retina

  • Most important part of the eye

  • Transduction of light energy into nerve impulses takes place

  • Order light passes after entering the eye: cornea, pupil/iris, lens, retina

  • Rods (black, white, gray) & cones (color) are receptor cells

  • 1. Light hits retina 2. bipolar cells 3. ganglion cells 4. optic nerve

• Fovea: where (in the retina) cones are most heavily concentrated and we have our best vision

• Blind spot: Where the optic nerve exits the retina, no rods & cones

• Accomodation: The process by which the eye’s lens changes shape to focus on far or near objects

• Blindsight: is visual processing without conscious awareness caused by damage to the visual cortex, such as a stroke or accident

• Young-Helmholtz theory of color vision: proposes there are 3 different types of color-sensitive cones (namely red, green and blue)

  • Also known as “additive color mixing” - if all colors were added together we would end up with the color white (mix of wavelenghts")

• Opponent-process theory of color vision: certain color-processing neurons oppose each other

  • Black & white; green & red; and yellow & blue that cannot be seen simultaneously because it’s against the law of physics.

  • Says that we derive color by subtracting colors from each other

• Says that light cells are processed while en route to the visual cortex - after they pass through the thalamus, which processes all the senses, except smell.

• Trichromats: people who have normal color vision

• Dichromats: people who are blind to either yellow-blue or red-green

• Monochromats: people who are totally color blind

• Sound is vibration

• Amplitude is the loudness of sound

• Pitch is a sound’s high-ness or low-ness

• Sound localization

  • The time-lag between left and right auditory stimulation.

  • order in which sound travels after entering the ear is as follows

  • 1. auditory canal 2. eardrum 3. middle ear (hammer, anvil, stirrup) 4. cochlea

• Cochlea:

  • Contains the auditory receptors

  • Takes the sound waves sent to it & triggers neural impulses (messages) which are sent to the temporal lobe’s auditory cortex

• Place theory (Helmholtz): the pitch we hear is related to the exact spot where the cochlea's basilar membrane is stimulated

  • Helmholtz’s Place Theory best handles high frequency sounds (5000 Hz and upward).

• Frequency Theory: the entire basilar membrane is vibrated by sound frequencies, not just in specific places

  • Frequency Theory’s big flaw is that these neurons do not have enough energy to keep firing to meet the demands of the incoming sounds

  • Frequency Theory’s specialty is low frequencies (under 1000Hz)

  Taste:

• Chemical-based

• Sweet, salty, sour & bitter

• Taste buds reproduce themselves every week

• 25% of people are supertasters

  25% of people are non-tasters

  50% of people are medium tasters

  Smell:

• Thalamus processes all of our senses but smell.

• Olfactory receptors recognize odors individually

• Chemical-based

• Sense of smell is from the olfactory bulb & olfactory nerves

• Sensory integration: the principle that one sense may influence another

  Touch:

• Touch means tactile

• Includes four basic sensations: pressure, pain, warmth, cold

• Has specially dedicated receptor cells

  Pain:

• Gate-control theory of pain (1965): a “functional gate” in the nervous system can let pain impulses travel upward to the brain or block their progress

• Sodium & potassium in the nerve cells have to do with pain

• Pain is “bottom-up” processing

  Pain and memory

• 1997 experiment:

  • Daniel Kahneman discovered overwhelmingly patients’ memories were dominated by the final and worst moments - not how long the pain lasted

• It’s better to taper down pain, rather than to turn it off abruptly

• Kinesthetic: sense of body movement

  • Sensation of your body’s position and movement such as the experience of bending one's knees or raising one's arms

• Vestibular: sense of balance

  • Body’s sense of orientation and balance

  • Semicircular canals are the center of our sense of balance

  Fight or flight, GAS (General Adaptation Syndrome).

• Physiological reaction to a perceived threat

• Body sense danger, will release hormones (adrenaline) to prepare us for fight or flight

• GAS is the body's response to stress from periods of time

1. Alarm stage: Fight or flight response

2. Resistance stage: Body adapting and recovering

3. Exhaustion phase

Describe sensory experience and apply to a unique situation

• Sensory experiences are sight, hearing, touch, smell and taste

• Taste is chemical bases and we have four parts of taste, sweet, salty, sour and bitter

• For example, if a person was lost in the woods and they stumbled across some berries and ate them, they is a possibility the berries have a sour taste

  • This has to do with survival; if the berries were sour, they were though to be poisonous