Sensation and Perception Flashcards
Sensation definition
Process by which sensory receptors and nervous system receive and represent stimuli
Perception definition
Process of organizing and interpreting sensory information
Bottom-up processing
- Data-driven
- Begins with incoming sensory information and continues to perception
Top-down processing
- Concept-driven
- Using pre-existing interpretation to interpret incoming sensory information
Vision
Light waves absorbed by photoreceptors in retina
Two types of photoreceptors
- Cones - bright lights, visual acuity, colors
- Rods - dim lights, peripheral vision
Visual acuity
Sharpness and precise detail
Two main theories of color vision
- Trichromatic theory
- Opponent process theory
Trichromatic theory
- Retina contains red, blue, green cones
- Related to initial processing in retina
Opponent process theory
- Red/green, blue/yellow, white/black cells
- Related to processing beyond retina
- Explains afterimages, blue/yellow colorblindness
Color Blindness
- Red/green most common - usually due to genetics but can be due to disease/injury
- Blue/yellow - due to genetics
Red/green color blindness (genetic mutation)
- Recessive gene on X chromosome
- More common in males (only have one X and only need one gene) than females (have two X and need gene on both)
Blue/yellow color blindness (genetic mutation)
- Autosomal (non-sex) dominant gene
- Affects males and females equally
Depth perception
Depends on binocular and monocular cues
Binocular cues
- Use both eyes
- Depth perception of close objects
- Retinal disparity and convergence
Monocular cues
- Use one eye
- Depth perception of far objects
- Size, overlap/position, linear perspective, texture, motion parallax
Retinal disparity
- Two eyes seeing objects from two different views
- Closer object = greater disparity
Convergence
Tendency of eyes to turn inward when an object is closer and vice versa
Gate control theory
- Pain perception
- Differentiates two types of nerve fibers in spinal cord
- “Gate” opens for pain signals (small unmyelinated) but closes for other sensory signals (large myelinated)
Two types of nerve fibers in spinal cord (gate control theory)
- Small unmyelinated - transmit most pain signals to brain
- Large myelinated - transmit other sensory signals to brain
Synesthesia
- Sensations in one modality spontaneously trigger sensations in another modality
- Most common = grapheme-color
- May be genetic, increased cross-activation and cross-connectivity in brain’s sensory areas
Grapheme-color synesthesia
Letters and numbers associated with colors
Psychophysics
Study of relationship between magnitude of physical stimuli and psychological sensations
Four psychophysics theories
- Weber’s Law
- Fechner’s Law
- Stevens’s Power Law
- Signal Detection Theory