Sensations

• Senses


  • Hearing (Audition)
  • Vestibular sense
  • Skin senses
  • Proprioception
  • Taste & Smell
  • Vision
• Hearing (Audition)


  • Changes in air pressure, or sound waves, vibrate the cilia on sensory neurons in the inner ear

  
• Vestibular sense


  • Hair cells sense movement of fluid in vestibular canals of inner ear to detect direction of motion
• Skin senses


  • Touch, heat, cold, pain, heavy pressure, hair movement
  • Each with its own type of sensory neuron, distributed under the surface of the skin
• Proprioception


  • Sensors on muscles report on how stretched the muscle is so we can tell if joint is open or closed
• Taste & Smell


  • Direct chemical senses
  • Receptors engage molecules of food or odor on receptors, in a lock and key fashion
  • 5 tastes (sweet, sour, bitter, salty, umami) each with their own receptor sites on tongue
  • Many smells
  • Around 350 different receptor sites, and countless combinations
• Vision


  • Visible light = electromagnetic radiation of wavelengths between 400 (violet) and 700 (red) nanometers (billionths of a meter)
  • Amplitude = brightness
  • Purity = saturation
  • Receptor organ=eye
  • Receptor cells are on back of the retina, concentrated in the fovea
  • Three kinds of cones are maximally sensitive to 3 wavelengths of light
  • Combining signals gives color information
  • No cones in periphery
  • Rods are sensitive receptors, distributed throughout the retina except at fovea
  • More summing of signals from rods = more sensitivity, less acuity
  • Signal Processing in the eye allows detection of contours (edges)
• Processing in primary visual cortex


  • Simple cells: Lines in a particular orientation
  • Complex cells: Two features of stimulus
  • Hypercomplex cells: Multiple features
• Specialties of the visual system


  • Edges, corners, movement, objects, faces
• Face Blindness / Prosopagnosia


  Damage or defect in fusiform gyrus (in temporal and occipital lobes)
• Perception


  Organizing and interpreting the data that the senses give us
• Bottom-up processing


  • Combining bits of information from multiple sources (e.g. neurons) to build a representation
• Top-down processing


  • Influence of beliefs, experiences and expectations on perception
• The goal of perception is not verbatim representation, the goal is assessment and prediction
• Depth Perception


  Constructing a three-dimensional representation from a 2-D image
• Gestalt Principles


  "The whole is greater than the sum of its parts"
• Gestalt Laws


  • Good form: When we perceive, we will always pick out form
  • Proximity: group objects, or features, which are close together
  • Continuity: group objects, or features, that form a contour
  • Similarity: group similar objects
  • Closure: fill in the gaps