PSYCH101: Introduction to Psychology

3a. Compare 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 understand our surroundings.
 
Sensation is when a sense receptor (such as the eye) detects a stimulus (such as light waves). Perception refers to how we interpret the information our sense receptors collect, such as recognizing a visual stimulus is a stop sign. You can think of sensation as a physiological process, whereas perception is psychological.
 
To review, see Sensation versus Perception and Sensation and Perception.
 

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

• How do the visual and auditory systems work? What are their components?
• How do the chemical senses work?
• How does the vestibular system contribute to our sense of balance and posture?

Our body works in several ways to experience sensory stimulation. Each sense has its own structure and system.
 
For example, we see images using our visual system when light waves enter our eyes (through the pupil), and the lenses in our eyes focus on them. This process projects the image on the fovea, a region of our retina. 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, which processes visual information.
 
In our auditory system, sound stimulation enters our auditory canal, causing vibrations in our eardrum, which in turn moves the ossicles. This movement causes the stapes to tap against the cochlea, which then causes the fluid inside the cochlea to vibrate. This leads to the movement of hair cells, which then send neural messages to the brain via the auditory nerve.
 
Our vestibular system relies on hair cells in the semicircular canals, which are adjacent to the cochlea, to convey information about the position of our head. Combined with information from muscles, skin, joints, and tendons, the vestibular system provides detailed information about body position and movement.
 
We have two chemical senses: taste (our gustatory system) and smell (our olfactory system). Gustation and olfaction rely on receptors to detect certain molecules and send sensory information to the brain.
                    
To review, see Sensation versus Perception, Sensation and Perception, Waves and Wavelengths, More on Waves and Wavelengths, Vision, Hearing, The Ear, Additional Senses, and Taste and Smell.
 

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

• What are the processes of transduction and sensory adaptation?

External stimuli, such as sound, touch, and smell, enter our sensory system. Sensory information is transmitted to the brain through the unique system each sense performs (see learning outcome 3b) from cells that are activated (and fire an action potential) when sensory information is perceived.
 
Transduction refers to how we convert sensory stimulus to an action potential. Sensory information must meet an absolute threshold for our body to perceive them – we call the information below this threshold subliminal messages. Sensory adaptation refers to when we no longer perceive constant or regular stimuli over an extended period of time.
 
To review, see Sensation versus Perception.

 

3d. Explain 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 concerns visual perception. Scholars in this discipline have developed several principles or laws to explain why we perceive images the way we do.
 
For example, Gestalt psychologists believe we separate images in a picture into a figure (what is in focus) and ground (background). According to Gestalt psychology, we tend to group items that are close together in accordance with the law of proximity. The principle of similarity suggests we group similar items together, such as a group of people wearing shirts that are the same color.
 
The law of continuity states we are prone to perceiving continuous, smooth, flowing lines rather than jagged, broken lines. The principle of closure suggests 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 Gestalt Principles of Perception, How Magicians Exploit Gestalt Principles, and Sensory Illusions.
 

Unit 3 Vocabulary

Be sure you understand these terms as you study for the final exam. Try to think of the reason why each term is included.

• auditory system
• external stimuli
• figure
• ground
• gustatory system
• law of continuity
• law of proximity
• olfactory system
• perception
• principle of closure
• principle of similarity
• sensation
• sensory adaptation
• sum of all parts
• transduction
• vestibular system
• visual system