Outline 2/19/2013 PSYC 120 General Psychology Spring 2013 Lecture 8: Sensation and Perception 1 Dr. Bart Moore bamoore@napavalley.edu Office hours Tuesdays 11:00-1:00 How we sense and perceive the world Sensory adaptation The visual system Please see me after class: Sarah Pagliero Ryan Paul Demetrius Prowell-Reed Ashley Rehm Giovanni Reynel Patricia Rochin Practice Question When a neuron is resting, the inside of the cell membrane is electrically, and the outside of the cell membrane is. Practice Question Motor commands from the right brain hemisphere control muscles in what part of the body? A. positive; negative B. negative; positive C. negative; negative D. positive; positive 1
Sensation Physical Energy (environment) Neural Signals (usually PNS) Perception Organization and interpretation of sensory signals The brain (CNS)! Just for fun The figure is moving Clockwise, or Counter-clockwise? Just for fun The figure is moving? Clockwise Counter-clockwise A little of both Same sensation Image on retina Different perception Based on your assumptions Bottom-up Processing versus Top-down Processing Two general ways that we process information 2
Bottom-Up Processing Data driven What is this? Sensation based Depends on info from sensory receptors Lines, angles, colors, sounds Parts are recognized and added together (integrated) What is this Bottom-Up Processing 3
Is this what you saw? Top-Down Processing Concept driven Guided by knowledge or expectations about the world Thoughts influence our perceptions A demo... A demo... If you re on this side of the room, close your eyes... If you re on this side of the room, get ready... 4
Switch! 5
All together, now... What do you see on the next slide 6
Stroop Effect Stroop Effect Sensation: How does information about our world get to our brain? Sensory Cortex Taste Smell Sensory (Afferent) Nerves Graded responses 7
Thresholds Signal Detection Theory Absolute Threshold Aware of and can detect sensory information Subliminal Perception Detect but are unaware of sensory information Difference Threshold Same or different? Detection based on Intensity of stimulus Sensitivity of individual Psychological state Experience Expectations Motivation Fatigue Perception Selective Attention Count the number of basketball passes the team in white clothing makes Directs & focuses psychological resources Inattentional Blindness 8
Change Blindness Links to the Nervous System Thalamus Sensory relay station/ gateway to cortex Except smell To other brain areas (cortex) How does a stimulus get into a sensory neuron? Transduction: Vision Transduction Physical energy signals (stimulus) Light Waves (stimulus) Electrical energy signals (action potentials) Receptors specific to each sense Vision: photoreceptors Electrical energy (neural impulse) 9
Vision: Light Waves Light: The Stimulus Input Light waves Hue (color) is determined by wavelength Distance from one peak to the next. Light: The Stimulus Input Light: The Stimulus Input Light waves Hue (color) is determined by wavelength Brightness is determined by the wave s amplitude (height) Light waves Hue Brightness Light waves bounce off objects in our environment and enter our eyes 10
Anatomy of the Eye The Retina Neural Message Photoreceptors Transduction Light Photoreceptors ganglion cell Ganglion cell axons = Optic nerve Blind spot Photoreceptors: Rods Light sensitive Dim light vision No color Periphery of retina Photoreceptors: Cones Color sensitive Need bright light Fine detail vision Fovea Dark adaptation 30 minutes to complete 11
Fovea Area of the retina with sharpest vision Fovea Photoreceptors Rods Cones Activity: Rods or Cones? Rods or Cones? 12
Rods or Cones? 13