jimtrue.com : school : PSY1012 : Chapter Five: Sensation

Posted by Jim True on February 13, 2006 6:20 PM. Last Updated October 22, 2006 9:23 PM

Disclaimer for all material noted here is at the bottom of this web page.

Chapter Five: Sensation

Sensation

• Sensation
• a process by which our sensory receptors and nervous system receive and represent stimulus energy. How we get input from the environment and change it into the language of the brain.
• Perception
• a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events. How we make the chaos of sensory information into a whole. The Jacket, sensory deprivation movie with Adrien Brody.
• Basic Principles
• Psychophysics - any type of energy that comes into our nervous system from the environment we experience the physical characteristic with a psychological experience. (ie sound waves (Volume), Light - Brightness, Pressure - weight, Taste - sweetness). We experience the energy that comes in psychologically.
• Sensation Thresholds
• Absolute Threshold
• minimum stimulatino needed to detect a particular stimulus 50% of the time
• Difference Threshold
• minimum difference between two stimuli required for detection 50% of the time
• just noticeable difference (JND)
• Weber's Law - SKIP
Sensory Adaptation
• diminished sensitivity as a consequence of constant stimulation. you don't notice it after you get used to the constant stimulation.
• Signal Detection Theory
• predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise).
• assumes that there is no single absolute threshold; everyone has a different sensitivity for detecting specific stimulus.
• detection depends party on person's:
• experience
• expectations
• motivation
• level of fatique
• Physical Properties of Waves [Vision & Audition]
• short wavelength = high frequency (bluish colors, high pitched sounds)
• Long wavelength = low frequency (reddish colors, low pitched sounds)
• Great amplitude (height of wave) (bright colors, loud sounds)
• Small amplitude (dull colors, soft sounds)

Vision

• Rods
• peripheral retina
• detect black, white and gray
• twilight or low light
• Cones
• near center of retina
• fine detail and color vision
• daylight or well-lit conditions
• 70% of the body's sense receptors are plugged into our eyeballs. Back of the eyes are the sense receptors that send information to the brain. We are diurnal (usually awake during the day), so our sensory receptors are adapted to daylight. Most animals are nocturnal so have a lot more rods than we do. Sensory Adaptation (when we leave a brightly lit room, we have to adjust to a brightly lit room. Called Dark Adaptation. Takes about 30 minutes for eyes to adjust from light to dark, but instananeously for dark to light.
• Optic Nerve
• nerve that carries neural impulses from the eye to the brain
• Blind Spot
• point at which the optic nerve leaves the eye, creating a "blind spot" because there are no receptor cells located there
• Fovea
• central point in the retina, around which the eyes cones cluster
• Visual Information Processing
• Trichromatic (three color) Theory
• Young and Helmholtz
• Three different retinal color receptors (red, green, blue)
• Some people are red-minus and have troubles distinguishing between red and green. Some people are green minus (most common). Sex-linked. Blue minus can occur in women. Others can occur with women, but much less common.
• Opponent Process Theory
• opposing retinal processes enable color vision. By exhausting the specific color cones, when looking at a neutral space, the other cones take over; the effect our eyes will automatically have an after image of the 'off' color.
• ON - Red green blue yellow black white
• OFF - Green red yellow blue white black

Audition (hearing)

• Audition
• the sense of hearing
• Frequency
• the number of complete wavelengths that pass a point in a given time
• Sound Waves are created by changes in air pressure
• Pitch
• a tone's highness or lowness
• depends on frequency
• prolonged exposure above 85 decibels produces hearing loss
• Conduction Hearing Loss
• hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea
• Nerve Hearing Loss
• hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerve

Body Position and Movement

• Kinesthesis
• the system for sensing the position and movement of individual body parts
• Vestibular Sense
• the sense of body movement and position
• including the sense of balance
• Aromatherapy - not a lot of research to back it up, but Alan Hirsch who runs the smell and taste. Sexually appealing fragrances to females: Licorice combined with cucumber; baby powder, pumpkin pie (11%); licorice and lavender arousing for men. turn-offs: cherry flavor, smell of charcoal.

Disclaimer: These are MY notes taken from classroom lectures while I'm in the classroom. While I'm perfectly happy to share my notes with my classmates and I know I take very good notes, you should still make every effort to attend the class and TAKE YOUR OWN NOTES. I will not transcribe everything the instructor says in the classroom, and I will NEVER post pre-exam reviews. My notes will not replace the value of actually attending class and taking your own class notes.I also cannot attest to their accuracy, other than they are what was provided in the lecture; you should not reference my notes as "expert opionion" by any means, and if you notice an error or omission, please do me the favor of e-mailing me with the correction and I will re-post my notes. End of Disclaimer.