AP Psychology: Sensation and Perception Notes

Key Takeaways: Sensation and Perception

  1. Understanding the specialized nature of each sensory system enables researchers to generate theories about how information is transmitted and develop treatments for disorders that result when these systems are impaired.
  2. After sensory information is transmitted to the brain, it must undergo additional processing to create perception. A variety of factors influence perception, including specific features of the information itself, the individual’s biological dispositions and past experience, and even cultural influences.
  3. The brain uses selective attention and other processes to manage the wide variety of stimuli it continually perceives and focus only on information deemed important.
  4. Many people believe in “paranormal” phenomena, such as extrasensory perception, but psychological research demonstrates that there is no empirical basis to parapsychological claims.

Key Terms: Sensation and Perception

Sensory Perceptions and Disorders

  • Sensation: The process by which sensory receptors receive information from the environment; includes vision, hearing, smell, taste, touch, and the vestibular and kinesthetic senses.
  • Transduction: Conversion of one form of energy into another, as when environmental stimuli are transformed into neural signals.
  • Receptors: Specialized structures that detect specific types of environmental stimuli and transduce them into neural signals.
  • Absolute threshold: The minimum stimulation required for a particular stimulus to be detected 50% of the time.
  • Just-noticeable difference (JND): The smallest change in stimulation that a person can detect 50% of the time.
  • Weber’s law: States that the size of the JND is directly proportional to the strength of the original stimulus.
  • Signal-detection theory (SDT): A theory that explains how individuals distinguish between meaningful sensory signals and random noise.
  • Cornea: The transparent, protective outer layer of the eye that bends light waves to assist in proper focus.
  • Iris: A piece of muscle tissue that sits behind the cornea and helps the eye adjust how much light enters. It gives the eye its color.
  • Pupil: A small, adjustable opening that is constricted or dilated by the iris. Constriction decreases the amount of light entering while dilation increases the amount of light entering.
  • Lens: A transparent structure that sits behind the pupil and can adjust its shape to bend light for proper focus (working with the cornea).
  • Accommodation: The process by which the lens changes shape to focus on near or far objects by adjusting how light hits the retina.
  • Sclera: The white part of the eye that provides structural support and contains blood vessels.
  • Retina: The light-sensitive inner surface of the eye containing a vast network of photoreceptors.
  • Photoreceptors: Specialized light-sensitive neurons in the retina that convert light into neural impulses; includes rods and cones.
  • Rod: A type of photoreceptor that processes black, white, and gray light; clustered in the retina’s periphery.
  • Cone: A type of photoreceptor that distinguishes colors and detects fine details in well-lit conditions; clustered in the fovea.
  • Fovea: A small indentation at the center of the retina that contains the highest concentration of cones.
  • Visual acuity: The ability to see fine details.


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