PSYC 101 Lecture Notes - Lecture 6: Psychophysics, Radiography, Retina
● What’s the difference?
○ Sensation
■ Detecting stimuli from the body or environment
○ Perception
■ Organizing sensations into meaningful patterns
○ Stimulus
■ Form of energy that can affect sense organs
● Sensation
○ Psychophysics
■ Study the relationship between stimuli and our psychological response to
them
○ Sensory receptors
■ Detect stimuli and convert energy into neural impulses
■ Receptors are designed to serve very specific function.
● Thresholds and Stimulus Change
○ Thresholds
■ There is a minimum amount of any given sensation that has to be present
for us to notice it
■ Absolute threshold
● This is the minimum amount of a stimulus that is necessary for us
to notice it 50% of the time
■ Sensory adaptation
● If a stimulus is unchanging,we become desensitized to it
● Keeps us focused on changes, not constants
● Just Noticeable Difference
○ Smallest difference in amount of stimulation that a specific sense can detect
○ Weber’s law
■ The size of the JND is a constant proportion of the initial stimulus
Vision
● Electromagnetic energy
○ Long wavelengths: AC circuits, radio waves, infrared rays
○ Short wavelengths: visible light, X-rays, UV and gamma rays
○ Other animals can see other segments of the spectrum of electromagnetic
energy
■ Bees can see ultraviolet rays and blue-violet, but not red
■ Pit vipers can see infrared rays
■ Dogs can’t see all the colors that humans can (no red)
The Eye (parts you need to know!)
● Lens
○ This flexible disk under the cornea focuses light onto the back of the eye
○ Accommodation
Document Summary
Form of energy that can affect sense organs. Detect stimuli and convert energy into neural impulses. Receptors are designed to serve very specific function. This is the minimum amount of a stimulus that is necessary for us to notice it 50% of the time. If a stimulus is unchanging,we become desensitized to it. Keeps us focused on changes, not constants. Long wavelengths: ac circuits, radio waves, infrared rays. Short wavelengths: visible light, x-rays, uv and gamma rays. Other animals can see other segments of the spectrum of electromagnetic energy. Bees can see ultraviolet rays and blue-violet, but not red. This flexible disk under the cornea focuses light onto the back of the eye. Muscle connected to the pupil that changes its size to let in more or less light. Light enters the eye through this opening. Contains the receptors that convert light to nerve impulses. Retinal cells that respond to particular wavelengths of light, allowing us to see color.
