Sensation and Perception
Agenda Test Sunday Sensation/Perception Processes Test Review 7:00 pm in B59 R1001 Sensation/Perception Processes Test Review
Sensation Sensation: Activation of sensory organs by energy from the environment. 1.) Detection: Receptor cells 2.) Transduction: encoding 3.) Transmission to brain Perception: Selecting, organizing, interpreting neural signals
Demonstration
The Right Side The duck loves to splash in deep puddles.
The Left Side The rabbit loves to hop in the tall grass.
Process Everyone Some People Bottom-Up Processing Top Down Processing Detects light Interprets contrasting intensities in space Assigns basic description Bottom-Up Processing Some People Interpret the images further Assign subjective meaning Top Down Processing
Bottom-up processing: Start at detection, then interpretation Top-down processing: Perception influenced by experience, motivation, expectations.
Reification: we see more spatial information than what is actually there.
Multistability: Switch between two different interpretations of an ambiguous image
Perception Laws Law of Closure Fill gaps in stimuli
Law of Proximity Group close figures together
Law of Similarity group together similar stimuli
Law of Continuity Perceive continuous patterns
Limited to Vision?
Sensation-Perception Interaction Perception is affected by other senses. Smell-Taste Hearing-Sight http://www.youtube.com/watch?v=G- lN8vWm3m0&feature=share
Detection Detection: the point at which our sensory organs are activated Absolute thresholds Smallest amount we can sense Detect 50% of the time
Absolute Thresholds
Detection Signal Detection Theory Sensory adaptation: Environment/Internal factors Signal/noise ratio Experience Expectations Motivation Fatigue Sensory adaptation: Detection decreases over prolonged exposure
Detection Just Noticeable Difference (JND): Minimum change needed to detect a difference. Weber’s law: The JND is a constant ratio. Light: 8% Weight: 2% Tones: 0.3%
Hearing Sound waves Amplitude: Frequency: height of wave, loudness length of wave, pitch.
Hearing Stereophonic hearing: locate sound. Sounds above, in front, behind Sound waves hit right ear before left
A Note On Transduction
Vision Amplitude: intensity Frequency hue
A Note on Anatomy Cornea bends light, protects eye Light passes through Pupil Opening adjusted by iris, sensitive to light intensity Lens focuses rays on back of the retina Fovea: central focal point. Blind spot: area where the optic nerve gathers together.
The Retina Rods Cones Detect color Detect black, white, gray Daylight Peripheral, twilight vision 120 million More light sensitive Cones Detect color Daylight Concentrated around the fovea 6 or 7 million More detail sensitive
Colorblindness Red-Green (most common) Blue-yellow also exists Sex linked: primarily affects males 7% Males, .4% Females
1. 2. 3. 4. 5. 6.
Touch Pressure Warmth Cold Pain
Pain What might influence pain? Attention, expectations, physiology, experience, cultural norms Phantom limbs
Gate-Control Theory of Pain What causes pain? Your brain Spinal cord can block pain transmission to brain Different types of nerve fibers Small = “open” neural gate Large = “close” gate Rubbing, electrical stimulation So do endorphins, distraction
Taste Sweet, Sour, Salty, Bitter Facts about taste: Umami? Not localized on tongue Evolution: fatty, sweet, salty Sour = rotted, bitter = poison