PSYCH101 Study Guide

Unit 3: Sensation and Perception

3a. Differentiate between the concepts of sensation and perception

  • What is the difference between sensation and perception?

We rely on our five senses (seeing, hearing, smelling, tasting, and touching) to make sense of the world. Sensory input allows us to make sense of our surroundings. Along these lines, we differentiate between sensation and perception. Sensation is defined as the specific sensory experience of a stimulus, for example, the act of hearing a sound, whereas perception refers to our interpretation of the information, like if we find the sound pleasant or distracting. Sensation can be thought of as a physiological process, whereas perception is psychological.

To review, see section 5.1 of the textbook and this lecture on sensation and perception.


3b. Explain the structure and function of the following sensory systems: visual, auditory, olfactory, somatic, and gustatory

  • How do the visual and auditory systems work? What are their components?
  • How do the chemical senses work?

Our body works in a number of ways to experience sensory stimulation. Each sense has its own structure and system. For example, we can see because light waves enter our eyes (through the pupil) and our eyes' lenses focus on it. Specifically, this focuses an image on a region of the eye's retina called the fovea. The fovea contains rods (best for dim light perception) and cones (best for bright light conditions) that help us see the image. The eye is connected to the optic nerve, which connects to various parts of the brain, including the occipital lobe that processes visual information.

Sound stimulation enters our auditory canal via vibrations in our eardrum which in turn moves the ossicles. This movement causes the stapes to press against the cochlea which then causes fluid inside the cochlea to move. This leads to an enlargement of hair cells which then send neural messages to the brain using the auditory nerve.

There are two chemical senses: taste and smell. Both gustation and olfaction rely on receptors in the tongue and nose to connect with appropriate molecules to send sensory information to the brain.

To review, see sections 5.4 and 5.5 of the textbook.


3c. Describe how external stimuli are processed in the brain

  • What is the processes of transduction and sensory adaptation?

External stimuli (e.g., sound, touch, smell) enter the sensory system. Sensory information is then sent to the brain through each sense's unique system (see 3b) from cells that are activated (and fire an action potential) when sensory information is perceived. Transduction refers to is the conversion from sensory stimulus to action potential. Sensory information must meet an absolute threshold in order to be perceived (information perceived below the threshold can be perceived as subliminal messages). Sensory adaptation refers to not perceiving constant/regular stimuli over an extended period of time.

To review, see section 5.1 of the textbook.


3d. Understand the principles of perception from Gestalt psychology

  • What is the figure-ground relationship?
  • What are the Gestalt principles of grouping?

The subfield of Gestalt Psychology is concerned with visual perception. These scholars developed a number of principles or laws explaining why we perceive images the way we do. For example, Gestalt psychologists posit that we separate images into a figure (what's in focus) and ground (background) when we view a picture.

According to Gestalt psychology, we also tend to group items that are close together, in what is known as the law of proximity. The principle of similarity suggests that we group similar items together, such as a group of people wearing shirts that are the same color. The law of continuity states that we are more likely to perceive continuous, smooth, flowing lines rather than jagged, broken lines. The principle of closure suggests that we organize our perceptions into complete objects rather than as a series of parts. As these laws demonstrate, Gestalt psychologists argue that we tend to perceive "the sum of all parts" when we view images.

To review, see section 5.6 of the textbook.


Unit 3 Vocabulary

This vocabulary list includes terms that might help you with the review items above and some terms you should be familiar with to be successful in completing the final exam for the course.

Try to think of the reason why each term is included.

  • Sensation
  • Perception
  • Adaptation
  • Transduction
  • Cornea
  • Pupil
  • Iris
  • Retina
  • Fovea
  • Lens
  • Trichromatic theory of color vision
  • Depth perception
  • Pinna
  • Ossicles
  • Cochlea
  • Pitch
  • Umami
  • Taste buds
  • Olfactory bulb
  • Thermoception
  • Pain perception
  • Vestibular sense
  • Proprioception
  • Kinesthesia
  • Figure-ground relationship
  • Law of proximity
  • Law of similarity
  • Law of closure
  • Law of continuity