EXAM 2: CH. 4-7

• Sensation is the process by which sensory organs in the eyes, ears, nose, mouth, skin, and other tissues receive and detect stimuli
• Sensation includes data-based processing, which is taking in data (what we hear, smell, etc.) from the environment that we process
• Sensation is earlier processing (sequentially), more biological  (sound waves) 
• Perception is the organization and interpretation of sensory stimuli by the brain
• Perception includes knowledge-based processing, which is later processing, more psychological
• With knowledge-based processing, you end up with a mental image of the stimuli you are exposed to
• Psychophysics is the study of relationships between the physical characteristics of stimuli, such as their intensity, and psychological experience because of them
• Psychophysics is sensation and perception together
• Absolute threshold is the minimum stimulation needed to detect a particular stimulus 50% of the time
• An example of an absolute threshold is a change from nothing to something
• Just noticeable difference (JMD) is the minimum difference between two stimuli required for detection 50% of the time
• An example of JMD is a change from something to either something more or something less (ex: change in intensity, change in volume of music)
• Weber’s law is that JNDs are proportional to the size of original stimulus (Proportional to where you started at (ex: ⅕ = 2/10 ))
• Bottom-up processing occurs when the brain collects basic information about incoming stimuli and prepares it for further interpretation (assembly, constructive)
• Top-down processing is the process of using information from previous experiences to make predictions about the world (filter or sort things from the world around you)
• • Human sensory systems
  • Energy sense
  • Vision
  • Hearing (audition)
  • Chemical sense
  • Taste (gustation)
  • Smell (olfaction)
  • Somatosenses (body senses)
  • Touch
  • Vestibular sense (balance)
  • Kinesthesis (movement, muscles/joints, etc)
• Receptor cells are specific receptor cells for each sense that stimulate neurons in the central nervous system. They also convert sensory input from the environment (sights, sounds, smells) to action potential
• Light that’s visible to humans is 400 nm - 700 nm
• The cornea is a transparent covering over the eye that brings it to the back of the eye
• The iris is the colored muscle, the pupil is the opening
• Iris controls the pupil; pupil gets big to let ambient light in, pupil gets small in daylight
• The lens focuses the visual image onto the back of the eye (retina), and it's a flexible structure that becomes less flexible over time.
• When looking at objects at a distance, the lens becomes thinner, nearby objects, the lens becomes thicker
• The retina is a thin sheet of tissue lining the back of the eye
• There are receptor cells in the retina
• The retina converts incoming light waves to action potentials
• The fovea is cones in the center of the retina and the location of maximum focus for certain kinds of images
• The optic disk is in the retina where the optic nerve exits the back of the eye; the blind spot where there are no receptor cells
• Your brain fills in the gap in the blind spot
• The optic nerve is the “power cord” bringing it out for the visual system, it goes to the thalamus
• The human eye goes from the cornea, iris and pupil, lens, retina, fovea, optic disk, and optic nerve
• Rods are concentrated in the periphery (the edge) of the retina
• There are more rods than cones in the periphery (the edge) of the retina
• Rods control black and white vision and are most active in dim illumination
• Cones are concentrated in the center of the retina (fovea)
• Cones control color vision are most active in bright illumination
• Rods and cones are found in the retina, but the fovea ONLY has cones
• The pinna is a funnel that starts to grab the sound waves from the environment and route them down to the auditory canal
• The auditory canal is a pathway that leads from pinna in the outer ear to the middle ear structure
• The eardrum vibrates to hear the sound