They are apart of one continuous process….but we will break them apart!

 Process by which our sensory systems receive stimuli from the environment and bring it to the nervous system  Systems have developed through natural selection  Differences do occur from person to person, but are relatively subtle  Process of interpreting sensory information  Organizing, recognizing, and using our sensory information  Individual differences are much more evident Example: Presidential Debate

 Analysis that begins with the raw materials that enters through our sense organs  Used by sensation  No prior knowledge, start from the bottom up  Analysis that uses the knowledge gained from prior experience with stimuli to perceive them  If the brain expects something  Without this, we would have to interpret the world like it was always new

 Our senses take in 11,000,000 bits of information per second  You only consciously process about 40  We cannot process all of the information converging simultaneously on our sensory systems  We use selective attention to prioritize input  Cocktail Party Effect  Ability to attend to only one voice among many  Ability to hear your name being called  People with ADHD appear to lack the ability to be selectively attentive; Instead of filtering out unimportant information, they focus on everything!

 Test Your Awareness Test Your Awareness

 The reduced response to an unchanging stimulus  After constant exposure to a stimulus, our nerve cells fire less frequently  Why do things we stare at not disappear then? Our eyes are actually always moving!  Bright lights, loud noises, etc. draw our attention  Why?  Allows us to focus on informative changes in our environment without being constantly distracted!  Example: clothing, smells  Advertisements: use novelty, change, and intensity to get our attention!

 Studying of relationship between stimuli (the physics part) and perception of those stimuli (the psyche or mind part)  Developed by Gustav Fechner

 Psychophysics has allowed us to establish the limits of awareness, or thresholds  Absolute Threshold: the smallest possible stimulus that can be detected 50% of the time; Can vary with age  Wing of a fly/bee from 1 cm  Drop of perfume in a 6 room apartment  Teaspoon of sugar in two gallons of water  Tick of a watch at 20 ft  Candle flame on a clear night 30 miles away  Differences Threshold (just noticeable difference – jnd): smallest difference between two stimuli that can be detected 50% of the time  The larger the stimuli, the larger the difference that is needed Easier to detect 5lb from 10lb than 400 from 405lb

 Mosquito Ringtones Mosquito Ringtones  FrequencyAge Range  8khzEveryone  10khz60 & Younger  12khz50 & Younger  14khz49 & Younger  15kh39 & Younger  16khz30 & Younger  17khz24 & Younger  17.4khz24 & Younger  18khz24 & Younger  19khz24 & Younger  20khz18 & Younger  21khz18 & Younger  22khz18 & Younger

 Ernst Weber  For their difference to be perceptible, two stimuli must differ by a constant proportion, not a constant amount  Found that we can detect  10% change in loudness  20% change in taste  2% change in weight

 Perception involves uncertainty  How do expectations affect your decisions? Personal feelings?  Is that a cop car behind you?  Signal Detection: Analysis of sensory and decision making processes in the detection of faint, uncertain stimuli; Predicts when we will detect weak signals  Adds cognitive process of decision-making to sensation  Want to understand why people respond differently to the same stimuli and why the same person’s reactions vary as circumstances change

 In experiments…  A faint stimulus is presented at times, other times no stimulus is detected  See number 4  Who cares?  Radiologists  Jury’s decision  Seismologist  Air traffic controller  Airport security  Soldiers

 Through the process of transduction  Receptor cells are present in all sensory systems  Take one form of energy (pressure, light waves, vibrations, heat, etc.) and turn it into a neural impulse  The ONLY thing you brain can understand  Entire process is called transduction  Doctrine of specific nerve energies: even if the impulse on your optic nerve isn’t light, you will “see”