Jayme Shadowens

 Senses = filters  Process incoming information  Physical stimulation into neural impulses that give us sensations  Sensation: the process by which stimulation of a sensory receptor produces neural impulses that the brain interprets as a sound, a visual image, an odor, a taste, a pain, or other sensory image  Perception: a mental process that elaborates and assigns meaning to the incoming sensory patterns  Perception creates an interpretation of sensation

 Aid survival  Directing towards stimuli (food, mates, shelter, friends)  Find pleasure in music, art, athletics, food, sex  Sensory receptors convert stimuli from outside world into neural signals that we can comprehend

 Transduction: transformation of one form of energy into another—especially the transformation of stimulus information into nerve signals by the sense organs  Step One:  Step One: detection by sensory neuron of the physical stimulus  Step Two:  Step Two: when the appropriate stimulus reaches a sense organ, it activates specialized neurons called receptors  Step Three:  Step Three: receptors convert their excitation into a nerve signal  Step Four:  Step Four: neural signal follows sensory pathway by the way of the thalamus to brain  Step Five:  Step Five: brain extracts information about the basic qualities of the stimulus

 Sensory adaptation: loss of responsiveness in receptor cells after stimulation has remained unchanged for a while  Unless it is intense or painful, stimulation that persists without changing in intensity for some other quality usually shifts into the background of our awareness A swimmer becomes adapted to the temperature of water You don’t continually notice the feel of the shoes on your feet

 Absolute threshold: the amount of stimulation necessary for a stimulus to be detected.  Presence or absence of a stimulus is detected ½ the time over many trials  Difference threshold: the smallest amount by which a stimulus can be changed  Difference can be detected ½ the time  Just noticeable difference (JND)

 Size of JND proportional to the intensity of the stimulus  Weber’s Law

 Fechner’s Law  Relationship between perceived magnitude and actual magnitude of stimulus  S = k log R (s = sensation, R = stimulus, k = a constant that differs for each sensory modality)  An increase in the physical magnitude progressively produces smaller increases in perceived magnitude

 Steven’s power law  More accurate than Fechner’s law  Covers wider variety of stimuli

 Classical theory of thresholds ignored the effects of the perceiver’s physical condition, judgments or biases  Signal Detection Theory  Explains how we detect signals  Sensation depends on the characteristics of the stimulus, the background stimulation, and the detector  Sensation is a judgment the sensory system makes about incoming stimulation The judgment a person makes about a sound they hear in the middle of the night all depends on their keenness of their hearing and what they expect to hear (mental state).