Detect Interpreting Environment taste smell attention Vestibular Sense Sensation and Perception Sensory Information Senses sight touch Kinesthesis processing Organizing brain hearing
Warmup What is sensation? What is perception?
Definitions Sensation-- the process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment. Perception--the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.
Top-down processing Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations. Bottom- up processing Analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information.
THEORIES OF SELECTIVE ATTENTION Bottom up Theories Top Down Theories
Top Down Theories of Attention • These theories say that perception starts from the more complex • Selective Attention/ Attenuation Theory: • We process everything but everything doesn’t reach the highest centers of processing • You “pick and choose” what to process the most • Ex. Cocktail Party Phenomenon
Bottom Up Theories of Attention • This theory says that perception starts with sensation • Because so much information is coming in, some sensory information is never processed • Filter Theory– We can’t process everything
Selective Attention • the focusing of conscious awareness on a particular stimulus. • You cannot pay attention to everything, only some things
Psychophysics The study of the relationship between physical characteristics of stimuli and our psychological experience of them • Light- brightness • Sound- volume • Pressure- weight • Taste- sweetness
Sensation- Thresholds • Absolute Threshold • minimum stimulation needed to detect a particular stimulus 50% of the time • Difference Threshold • minimum difference between two stimuli required for detection 50% of the time • just noticeable difference (JND)
Selective Attention • List 10 things you saw in the picture…..
Inattentional Blindness • failing to see visible objects when our attention is directed elsewhere. • Change Blindness (failing to notice changes in the environment) • Choice Blindness • Choice Blindness Blindness
Sensation- Thresholds • Signal Detection Theory • predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) • assumes that there is no single absolute threshold • detection depends partly on person’s • experience • expectations • motivation • level of fatigue • Priming • the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response.
ThresholdsSignal Detection • Signal-detection theory • Ratio of “hits” to “false alarms”
100 Percentage of correct detections 75 50 Subliminal stimuli 25 0 Low Absolute threshold Medium Intensity of stimulus Signal Detection is not necessarily true… • Subliminal • When stimuli are below one’s absolute threshold for conscious awareness
Sensation- Thresholds • Weber’s Law- to perceive as different, two stimuli must differ by a constant minimum percentage • light intensity- 8% • weight- 2% • tone frequency- 0.3% • Sensory adaptation- diminished sensitivity as a consequence of constant stimulation
Wrap-up TICKET OUT: What are sensation and perception? How does our perceptual system help us to interpret the world around us? Explain. Short Video About Sensation and Perception
Warm up How does the visual system work?
Vision • Pupil- adjustable opening in the center of the eye • Iris- a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening (dilates in response to changing light intensity) • Lens- transparent structure behind pupil that changes shape to focus images on the retina • Cornea- outer covering of the eye • Retina- the light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information. • Blind Spot - the point at which the optic nerve leaves the eye, creating a “blind” spot because no receptor cells are located there • Fovea- the central focal point in the retina, around which the eye’s cones cluster. • Optic Nerve- the nerve that carries neural impulses from the eye to the brain
Distal Stimulus– the object in the outside world Proximal Stimulus– the object as it is projected on the retina (upside down)
This is how we see Animation of how this works... TERMS: Distal stimulus, proximal stimulus, fronto-parallel plane, Distal Object, Percept
Visual Information ProcessingFeature Detection • Feature detectors
Visual Information ProcessingParallel Processing • Parallel processingsimultaneous processing of several aspects of a problem simultaneously • Blind sight
What is color? • Color is the psychological attribute given to our response to different wavelengths of visual light • It is psychological because it is perceived • Humans can only perceive colors on the visual spectrum. Perception has to do with light getting reflected off an object and onto the different types of cones in the eye
The Stimulus Input: Light Energy Transductionconversion of one form of energy to another In sensation, transforming of stimulus energies into neural impulses Wavelengththe distance from the peak of one wave to the peak of the next Hue(color) Dimension of color determined by wavelength of light Intensity Amount of energy in a wave determined by amplitude