Sensation: Detection of stimuli

Perception: Interpretation, identification, and organization of sensory information

Sensation & Perception

Sensation: Detection of stimuli

The Senses

Vision LightHearing Sound wavesTouch Pressure, temperatureTaste ChemicalsSmell Chemicals

Balance GravityKinaethesia Movement

Proprioception Limb position

Sensation Bottom-Up Processing

analysis that begins with the sense receptors and works up to the brain’s integration of sensory information

reflects physical stimuli veridically (accurately)

•Absolute threshold - The minimum amount of energy our senses can consciously detect 50% of the time.– Vision – candle flame at 30 miles– Hearing – ticking watch at 20 feet– Taste – 1 tsp sugar in 1 gal water– Smell – 1 drop perfume through 3 rooms– Touch – bee wing falling on face at 1 cm

Sensation - Thresholds

Difference Threshold Also called “just noticeable difference” or JND

the smallest difference between two stimuli that is detectable 50 percent of the time

Smallest detectable difference between two stimuli

Adaptation & Habituation

Sensory adaptation - tendency of sensory receptors to fatigue and stop responding to an unchanging stimulus. This is a physical, bottom-up process

Habituation

Habituation - tendency of the brain to stop noticing constant, unchanging information. Example – your clothing, fan noise, perfume!

Psychophysics study of the relationship between physical characteristics of stimuli and our psychological experience of them

Light- brightness Sound- volume Pressure- weight Taste- sweetness

1. Perceptual cues are used 2. Perception is active, constructive3. Perceptual interpretations can be

wrong (illusions)4. Perception is affected by experience

Perception

Perception Top-Down Processing

information processing guided by higher-level mental processes

when we construct perceptions by drawing on our experience and expectations

Often imposes a meaning that does not exist in the physical stimulus (not veridical)

Top Down Processing• Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.

• Amzanig huh?

Perceptual Organization

• Top- down process (individualized by experience)

• how your brain makes sense of the world, which includes “hiding” from you certain changes in stimuli so that the stimuli continue to appear constant to you

Gestalt Principles of Perception

Perception of Depth

• Images on the retina are 2-D• How do we perceive 3-D (depth)?

• CUE approach – we learn the connection between cues and depth through experience, yielding 3-D perceptions

Binocular Cues• Binocular cues - cues for perceiving depth based on both eyes.1.retinal disparity

images from the two eyes differ closer the object, the larger the disparity

2. convergence neuromuscular cue two eyes move inward (converge) more as objects get nearer

Monocular Cues• Monocular cues (pictorial

depth cues) – cues for perceiving depth based on one eye only.1.Linear perspective 2.Relative size 3.Interposition (overlap)

4.Texture gradient 5.Motion parallax Menu