Sensation and Perception Flashcards
Sensation
Definition: The process by which sensory receptors and the nervous system receive and represent stimulus energies from the environment.
Example: Feeling the warmth of sunlight on your skin.
Perception
Definition: The process of organizing and interpreting sensory information to recognize meaningful objects and events.
Example: Recognizing a friend’s face in a crowd.
Bottom-up Processing
Definition: Processing that begins with incoming sensory information and proceeds up to the brain for interpretation.
Example: Noticing the details of individual puzzle pieces before seeing the whole picture.
Top-down Processing
Definition: Processing that begins with the brain’s use of preexisting knowledge and expectations to interpret incoming sensory information.
Example: Seeing a cloud and interpreting its shape as resembling an animal.
Vision
The physical stimuli for vision are light waves that are absorbed by photoreceptors (light-sensitive receptors) in the retina.
The two types of photoreceptors
The two types of photoreceptors are cones and rods.
Theories of Color Vision
Trichromatic theory and opponent process theory are the main theories of color vision.
Cones
Cones are photoreceptor cells in the retina that are responsible for color vision and visual acuity in bright light conditions. They are most densely concentrated in the fovea, the central region of the retina, and are less sensitive to dim light compared to rods.
Rods
Rods are photoreceptor cells in the retina that are responsible for vision in low light conditions (scotopic vision) and peripheral vision. They are more sensitive to dim light but do not perceive color, contributing to our ability to see in low-light environments. Rods are more densely distributed in the peripheral regions of the retina.
Trichromatic Theory
Explanation: The retina contains three types of color receptors (cones) - red, blue, and green.
Example: Seeing a wide range of colors due to the combination of these three cone types.
Opponent-Process Theory
Explanation: Proposes the existence of opponent-process cells responsible for perceiving red/green, blue/yellow, and white/black.
Example: Experiencing a negative afterimage after staring at a colored image for a long time.
Depth Perception
Definition: The ability to perceive depth and distance.
Example: Judging how far away a tree is from you in a forest.
Binocular Cues
Definition: Depth cues that depend on the use of both eyes.
Example: Retinal disparity - the difference between the images projected onto each eye.
Monocular Cues
Definition: Depth cues that depend on the use of one eye.
Example: Linear perspective - parallel lines appear to converge in the distance.
Pain
Pain is caused by several types of stimuli including extreme temperatures, mechanical pressure, and electrical stimulation, and its perception is moderated by several factors including current emotional state and past experience with pain
