Sensation and Perception

Sensation and Perception

1. Psychophysics: Basic Concepts and Issues

   • Thresholds: Looking for limits
     • Threshold: Dividing points between energy levels that do and do not have a detectable effect
       • JDN: smallest difference in the amount of stimulation that a specific sense can detecct
         • Weber's law: size of noticeable difference is a constant proportion of size of the initial stimulus
     • Signal Detection theory: detection of stimuli involves decision processes as well as sensory process, which are both influenced by a variety of factors besides stimulus intensity
     • Perception without Awareness: Subliminal perception- sensory input without conscious awareness
     • Sensory adaptation: gradual decline in sensitivity due to prolonged stimulation

2. Our sense of Sight: The Visual System

   • Stimulus: light- is a form of electromagnetic radiation that travels as a wave, moving enough at the speed of light
   • The Eye: creates an image of the visual world
     • Lens: transparent eye structure that focuses the light rays falling on the retina.
       • Farsighted and nearsighted
         • Pupil: helps regulate the amount of light passing into the rear chamber of the eye
   • The retina: absorbs light, process images, sends visual information to the brain
     • Visual receptors: rods and cones
       • Dark and light adaptation
         • Information processing in the retina
   • Vision and the Brain
     • Visual pathways to the brain- Optic chiasm- optic nerves from the inside half of each eye cross over and then project to the opposite half of the brain
       • Information processing in the visual cortex
   • Viewing the world in Colour
     • The stimulus for colour: subtractive colour mixing and additive mixing
       • Trichromatic Theory of Colour Vision- the three different type of receptors with different sensitives to different light wavelengths
         • Opponent Process theory of colour vision
           • Complementary colours and afterimage

3. The Visual system: Perceptual Processes

   • Perceiving forms, patterns, and objects
     • Reversible figure- drawing that is compatible with two interpretations that can shift back and forth
       • Perceptual set- Readiness to perceive a stimulus in a particular way
         • Assembling forms: Feature analysis, bottom up processing, top-down processing, subjective contours
   • Looking at the Whole Picture: Gestait Principles
     • Figure and ground, Proximity, closure, similarity, simplicity, and Continuity
       • Formulating Perceptual Hypotheses
   • Perceiving Depth and Distance
     • Depth perception: involves interpretation of visual cues that indicate how near or far away objects
       • Binocular Cues: clues about the distance based on the differing views of the two eyes
         • Monocular Cues: clues about distance based on the image in wither eyes alone
   • Perceptual Constancies In Vision
     • Perceptual constancy: tendency to experience a stable perception in the face of continually changing sensory input
   • The Power of Misleading Cues: Optical Illusions
     • Optical Illusions: inexplicable discrepancy between he appearance of visual stimulus and its physical reality
       • Different illusions- Muller-Lyer illusion, The ames room, A monster illusion

4. Our sense of Hearing: The auditory system

   • The Stimulus: Sound
     • sounds waves are vibrations of molecules, which means that they must travel through some physical medium, such as air
   • Hearing Capacities
     • Wavelengths of sound are described in terms of their frequency which are then measured in cycles per second
   • Sensory Processing in the ear
     • Ears channel energy to the neural tissue that receives it
       • Different parts of the ear: External ear- Pinna, Middle ear- three tiny bones (Hammer, anvil, strirrup, inner ear- cochlea, basilar
   • Auditory perception: theories of hearing
     • Place theory: holds that perception of pitch corresponds to the vibration of different portions, or places, along the basilar membrane
       • Frequency theory: holds that perception of pitch corresponds to the rate, or frequency, at which the entire basilar membrane vibrates

5. Our Chemical senses: Taste and smell

   • Taste: the gustatory system
     • Gustatory system: the sensory system for taste
   • Smell-The Olfactory system
     • Pheromones are chemical messages. they can be sent by one organism and recieved by another member of the same species

6. Sense of touch: Sensory systems in the skin

   • Feeling pain
     • Pathways to the Brain
       • Two path ways slow and fast.
   • Puzzles in Pain perception
     • Pain can be influenced by personality, mood and other factors. its is not automatic.
   • Gate-controlled theory: holds that incoming pain signals can be blocked in the spinal cord. endorphins and a descending neural pathway appear to be responsible for the suppression of pain by the central nervous system.

7. Our other senses

   • Kinesthetic system: the positions of the various parts of the body
   • The Vestibular system
     • responds to gravity and keeps you informed of your body's location in space