ch.4

• sensation - the process by which our sensory receptors and nervous system receive stimulus energies from our environment
• sensory receptors - sensory nerve endings that respond to stimuli
• perception - process of organizing and interpreting sensory information; bringing meaning to sensations
• bottom-up processing - analysis that begins with sensory receptors traveling to the brain to integrate sensory information
• top-down processing - information processing guided by higher-level mental processes by drawing on our experiences and expectations
• selective attention - the focusing of conscious awareness on a particular stimulus
• cocktail party effect - ability to attend to one voice among a sea of other voices
• inattentional blindness - failing to see visible objects when our attention is directed elsewhere
• change blindness - failing to notice changes in the environment
• sensory receptors convert incoming stimuli information into electrochemical signals aka neural activity
• transduction - conversion of stimulus energies into neural impulses
• transduction process - information goes to the thalamus and then to various areas in the brain
• transduction processes

  • light energy to vision
  • chemical energy to smell and taste
  • sound waves to sound
• our sense organs are change detectors
• sensory adaptation - diminished sensitivity as a consequence of constant stimulation
• sensory thresholds - the point at which sensations begin and end
• absolute threshold - the minimum stimulus energy needed to detect a particular stimulus 50 percent of the time
• difference threshold - the minimum difference between two stimuli required for detection 50 percent of the time; aka just noticeable difference (jnd)
• psychophysics - study of relationships between the physical characteristics of stimuli and our psychological experience of them
• Gustav Fechner - studied absolute thresholds
• signal detection theory - predicts how and when we detect the presence of a faint stimulus amid background stimulation; assumes there is no absolute threshold and that detection depends partly on a person's experience, expectations, motivations, and alertness
• reactions to a stimulus can be categorized as

  • hit - correct identification of something you should say yes to
  • miss - miss something you should have said yes to
  • false alarm - say yes to something you should say no to
  • correct rejection - properly say no to something you should say no to
• weber's law - to be perceived as different, two stimuli must differ by a constant minimum percentage, not an amount
• subliminal - below one's absolute threshold for conscious awareness
• laws of sensation

  • fechner's law
  • steven's power law
• fechner's law - size of jnd is proportional to the intensity of the stimulus; jnd is large when intensity of stimulus is high
• steven's power law - law of magnitude that is more accurate than fechner's law and covers a wider variety of stimuli
• priming - activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response
• habituation - lower centers of brain that filter sensory stimulation ignore or prevent conscious attention to stimuli that don't change; sensory receptors respond to stimulation but no signal is sent to the cortex
• micro saccades - constant movement of the eyes
• wavelength - distance from peak to peak of a wave
• hue - dimension of colour that is determined by the wavelength of light; the colour we experience
• intensity - amount of energy the wave contains; is determined by the wave's amplitude
• amplitude - a wave's height
• cornea - the clear, protective outer layer of the eye that bends light to help provide focus
• pupil - adjustable opening in the center of the eye where light enters
• iris - a ring of coloured muscle tissue that dilates or constricts in response to light intensity
• lens - transparent structure behind the pupil that changes chape to help focus images on the retina
• retina - the light-sensitive inner surface that contains rods, cones, and layers of neurons that begin the processing of visual information
• accommodation - process by which the eye's lens changes shape to focus near or far objects on the retina