SENSATION N PERCEPTION, VISION, OLFACTORY ETC

• Sensation


  Involving simple "elementary" processes that occur right at the beginning of a sensory system, as when light stimulates receptors in the eye
• Perception


  Identified with complex processes that involve memory and higher-order mechanisms such as interpretation and activity in the brain
• Both the biological and psychological levels of analysis, a distinction is often made between sensation and perception
• Biological level


  • Sensory processes involve the sense organs and the neural pathways that emanate from them, which are concerned with the initial stages of acquiring stimulus information
  • Perceptual processes involves higher levels of the Cortex, which are known to be more related to meaning

  
• Psychological level


  • Sensations are fundamental, raw experiences associated with stimuli
  • Perception involves the integration and meaningful interpretation of these raw sensory experiences
• Sensory systems


  • They provide important information about the surroundings
  • They are used to successfully navigate and interact with the environment to find nourishment, seek shelter, maintain social relationships, and avoid potentially dangerous situations
• Sensory receptors


  Specialized neurons that respond to specific types of stimuli. When sensory information is detected by a sensory receptor, sensation has occurred
• Absolute threshold


  The minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time
• Measuring absolute thresholds


  1. Signal detection - Presenting stimuli of varying intensities to a research participant to determine the level at which they can reliably detect stimulation

  2. Method of limits - Presenting increasingly louder/dimmer stimuli to determine the point at which the participant begins to detect the stimulus
• Every individual has different thresholds
• Subliminal messages

  Messages presented below the threshold for conscious awareness that are received but not consciously perceived
• Just noticeable difference (JND) or difference threshold

  The minimum difference in stimuli required to detect a difference between them

  
• Other sensory systems


  • Vestibular sense (spatial orientation and balance)
  • Proprioception (position of bones, joints, and muscles)
  • Kinesthesia (limb movement)
  • Somatosensation (touch)
  • Nociception (pain)
  • Thermoception (temperature)
• Sensory transduction


  The conversion of sensory stimulus energy to action potential or neural activity
• Sensory processes


  1. Reception - Activation of sensory receptors by stimuli

  2. Transduction - Transformation of physical energy into neural impulses
• Distal stimulus


  The stimulus "out there" in the environment, as opposed to the proximal stimulus which is the image on the retina
• Visual transduction


  Transformation of light energy into electrical energy by visual pigments in the retina
• Neural processing


  The changes in neural signals as they are transmitted through the nervous system
• Sound waves


  • Amplitude (loudness)
  • Frequency (pitch)
  • Complexity (timbre)

  
• Perception


  The psychological process of making sense of sensory information from the environment
• Perceptual set

  A tendency to view things only in a certain way, influenced by factors like past experiences, expectations, motivations, beliefs, emotions, and culture
• Schema


  A collection of basic knowledge about a concept or entity that serves as a guide to perception, interpretation, imagination, or problem solving
• Perception process

  1. Selecting information and sensory selection - Focusing attention on certain incoming sensory information

  2. Organizing information - Sorting and categorizing perceived information based on innate and learned cognitive patterns

  3. Interpreting information - Assigning meaning to experiences using mental structures called schemata
• Factors influencing sensory selection

  • Need
  • Interest
  • Expectations
  • Physiological limitations
• Not all sensations result in perception, as we often don't perceive stimuli that remain relatively constant over prolonged periods
• Perception


  The process of taking the stimuli and putting it into some pattern we can recognize. Process of grouping and segregation.
• Gestalt Psychology

  Addresses how we translate external stimuli into mental images or how we process blending external stimuli with internal processes
• Interpreting information


  The third part of the perception process, in which we assign meaning to our experiences using mental structures known as schemata
• Schemata


  Databases of stored, related information that we use to interpret new experiences
• Sensory adaptation

  • We often don't perceive stimuli that remain relatively constant over prolonged periods of time
• Attention


  Plays a significant role in determining what is sensed versus what is perceived
• Inattentional blindness


  The failure to notice a fully visible, but unexpected, object or event when attention is devoted to something else
• Inattentional deafness


  The auditory analog of inattentional blindness. People fail to notice an unexpected sound or voice when attention is devoted to other aspects of a scene

  
• Dichotic listening


  A task in which different audio streams are presented to each ear. Typically, people are asked to monitor one stream while ignoring the other
• Selective listening


  A method for studying selective attention in which people focus attention on one auditory stream of information while deliberately ignoring other auditory information
• Motivation


  Can affect perception by shifting our ability to discriminate between a true sensory stimulus and background noise
• Signal detection theory


  The ability to identify a stimulus when it is embedded in a distracting background
• Our perceptions can be affected by our beliefs, values, prejudices, expectations, and life experiences
• The shared experiences of people within a given cultural context can have pronounced effects on perception
• Perceptual differences were consistent with differences in the types of environmental features experienced on a regular basis by people in a given cultural context