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• Perceptual organization


  Constructing our view of the world
• Perception


  A constructive process by which we go beyond the stimuli that are presented to us and attempt to construct a meaningful situation
• We do not just passively respond to visual stimuli that happen to fall on our retinas. Instead, we actively try to organize and make sense of what we see.
• Gestalt laws of organization


  • Describe how we organize bits and pieces of information into meaningful wholes
  • Set forth in the early 1900s by a group of German psychologists who studied patterns, or gestalts
• Most common principles of gestalt theory

  • Proximity
  • Similarity
  • Good continuation
  • Closure
  • Good form
  • Symmetry
• Proximity


  Items which are close together in space or time tend to be perceived as belonging together or forming an organized group
• Similarity


  Same things are considered one thing. Similar items tend to be organized together
• Good continuation


  The tendency to perceive a line that starts in one way as continuation in the same way
• Closure


  Perceptual processes that organize the perceived world by filling in gaps in stimulation
• Good form


  A type of closure. We fill in the gaps perceive form rather than disconnected lines
• Symmetry


  There is a tendency to organize things to make a balanced or symmetrical figure that includes all the parts
• Feature analysis


  Considers how we perceive a shape, pattern, object, or scene by reacting first to the individual elements that make it up

  
• Individual neurons in the brain are sensitive to specific spatial configurations, such as angles, curves, shapes, and edges
• When we encounter a stimulus such as a letter our brain's perceptual processing system initially responds to its component parts
• Each of these parts is compared with information about components that is stored in memory
• When the specific components we perceive match up with particular components that we have encountered previously, we are able to identify the stimulus
• Top-down processing


  Perception is guided by higher-level knowledge, experience, expectations, and motivations
• Bottom-up processing


  Recognizing and processing information about the individual components of the stimuli
• Top-down and bottom-up processing occur simultaneously, and interact with each other, in our perception of the world around us
• Perceptual constancy


  Our ability to see things differently without having to reinterpret the object's properties
• Types of perceptual constancy

  • Size constancy
  • Shape constancy
  • Brightness constancy
• Size constancy


  Our ability to see objects as maintaining the same size even when our distance from them makes things appear larger or smaller
• Shape constancy


  Our ability to perceive that an object is still the same shape even though the angle from which we view it appears to distort the shape

  
• Brightness constancy


  Our ability to recognize that color remains the same regardless of how it looks under different levels of light
• Depth perception


  The ability to view the world in three dimensions and to perceive distance
• Binocular disparity


  The difference in images that reach each retina due to the distance between the eyes, which allows the brain to estimate the distance of an object
• Monocular cues


  Cues that permit us to obtain a sense of depth and distance with just one eye, such as motion parallax
• Movement perception


  The process through which humans and other animals orient themselves to their own or others' physical movements
• The eye is by far the most effective organ for sensing movement
• Some cells in the visual area of the cat's brain respond only to moving stimuli, with sets of movement-detector cells functioning specifically for each direction across the field of view
• Perceptual illusions


  Indicate that our mind does not always accurately represent the perceptual input, suggesting that the mind is actively involved in interpreting the perceptual input rather than passively recording it
• Psychophysics


  The study of quantitative relations between psychological events and physical events or, more specifically, between sensations and the stimuli that produce them
• Psychophysics


  • It is functional, because the processes of the sensory systems are of interest, rather than their structure (physiology)
• Absolute sensitivity


  The limits of the organism's capacity to respond to stimulation, inversely related to the minimum stimulus which can be detected reliably by a subject
• Differential sensitivity


  The organism's capacity to respond to differences, both qualitative and quantitative, between stimuli, inversely related to the minimum difference between stimuli needed for reliable discrimination
• Absolute threshold


  The stimulus value which yields a response 50 percent of the time, a statistical concept due to inherent variability
• Differential threshold


  The stimulus difference which gives rise to a judgment of different 50 percent of the time
• Point of subjective equality


  The comparison stimulus which is most likely to result in a judgment of 'same' when compared to a fixed stimulus
• Thresholds are the point of intensity at which the participant can just detect the presence of, or difference in, a stimulus</b>
• Absolute threshold


  The level of intensity of a stimulus at which the subject is able to detect the presence of the stimulus some proportion of the time