Chapter 5: Sensation and Perception

Sensation and Perception

• Sensation

  • Definition: Occurs when sensory information is detected by a sensory receptor.
  • Process: The initial stage where stimuli from the environment are converted into neural signals.

• Perception

  • Definition: The process by which sensory information is organized, interpreted, and consciously experienced.
  • Importance: It shapes how we understand and interact with the world, influenced by personal experiences and context.

• Bottom-up Processing

  • Definition: A method of processing where perceptions are built from the ground up using sensory input.
  • Example: Recognizing a red apple based solely on its color, shape, and texture without prior knowledge of what it is.

• Top-down Processing

  • Definition: Interpretation of sensations is influenced by existing knowledge, experiences, and thoughts.
  • Example: Reading jumbled words in a sentence by filling in gaps using context from the rest of the sentence.

• Muller-Lyer Illusion

  • Definition: An optical illusion where two lines of the same length appear different due to the orientation of arrowheads at their ends.
  • Importance: Demonstrates the difference between actual size and perceived size influenced by contextual cues.

Anatomy of the Eye

• Cornea

  • Definition: A transparent covering over the eye.
  • Function: Light waves are transmitted across the cornea, aiding in the initial focus of light.

• Pupil

  • Definition: A small opening in the eye that allows light to enter.
  • Dynamics: The size of the pupil changes in response to light levels and emotional arousal, regulating the amount of light that enters.

• Iris

  • Definition: The colored portion of the eye surrounding the pupil.
  • Function: Contains muscles that control the size of the pupil, thus regulating light entry.

• Lens

  • Definition: A curved transparent structure located behind the iris.
  • Function: Further focuses light onto the retina, playing a critical role in vision clarity.

• Retina

  • Definition: The light-sensitive lining located at the back of the eye.
  • Function: Contains photoreceptor cells (rods and cones) that convert light into electrical signals sent to the brain for visual processing.