Chapter 4: Sensation and Perception

Chapter 4: Sensation and Perception

1. Sensation Vs. Perception

   • Sensation: the stimulation of a sense.
   • Perception: an awareness or view created by the mind as a result of sensory input.

2. Basic concepts

   • Threshold
     • Deff: the point (50%) where stimulus can be detected
     • Absolute Threshold: the absolute minimum amount of stimulus an organism can detect.
     • Just Noticeable Difference (JND): the smallest amount of change an organism can detect.
     • Weber's Law: the size of the JND is in proportion to the stimulus.
   • Signal-Detection Theory: involves both detection and sensory processesand are both influenced by a number of other factors.
   • Subliminal Perception: registration of sensory input without conscious awareness.
   • Sensory Adaption: the gradual decress in sensitivity due to prolonged exposure to a stimulus.

3. Vision and sight

   • Eye Diagram
   • The stimulus for sight is light.
   • The human eye only sees a small portion of the light spectrum known as visible light. (ROYGBIV= White Light)
   • Pathway of Light: Light-cornea-anterior chamber- pupil (through iris)-lens-anterior chamber- retina (rods and cones)- choride layer or to the Optic nerve- Occipital lobe.
   • Optic Chiasm: where the nerves in the eyes cross over.
   • Trichromatic theory: There are three types of receptors (Red, Green, Blue) that have different sensitivities and can detect any combination of colours using theses.
   • Colour blindness: occurs when a genetic deficiency effects the ability to tell colours appart.

4. Auditory and sound

   • sound waves are the stimulus for hearing.
   • Place theory: the perception of sound is related to the vibration in diffrent locations in the basiler membrane.
   • Frequency Theory: is the relation to the rate the basilar membrane vibrates at.

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