Topic 1: Introduction to Perception Flashcards
In what terms can perception be described in?
can be defined in terms of sensory processes, like receptor activation and neural firing
or in terms of mental activity that mediates between sensation and awareness, interpreting what our senses tell us (subjective experience)
What is the definition of sensation?
process of encoding energy or chemicals in the environment in terms of neural signals
a basic experience elicited by a simple stimulus
more concerned with your own physical experience (ego centric)
e.g. feeling of warmth on your skin
What is the definition of perception?
organization and interpretation of neural signals, making them meaningful
more complex conscious experiences produced by integrating sensations
more concerned with identifying the stimulus
e.g. you see a glowing red stove element, producing heat you feel; you know it is 50 cm away, and it can burn you
Why do we study perception for understanding?
to determine how underlying mechanisms function
first step in understanding cognition (e.g. mind-body relationship)
to know why the world looks. sounds, feels, tastes, and smells the way it does
Why do we study perception to solve practical problems?
to develop solutions for the sensory impaired (e.g. Braille, glasses)
to understand the practical applications of illusions
to produce substitutes for the world (e.g., stereo sound, surround sound)
to produce substitutes for the observer (e.g. robotic vision)
What is the central problem in perception?
the world is three-dimensional
the image on our retina is 2-D
yet we think of the world in 3-D
this problem is called underdetermination
What is a distal stimulus?
the object in the world
e.g. an apple, a finger poking your arm, a vibrating string
What is a proximal stimulus?
the pattern of energy or chemicals impinging on our receptors
e.g. pattern of photons on your retina; kinetic energy on your skin; sound energy hitting your eardrum
How do we go from an underdetermined proximal stimulus produced by a distal stimulus, and arrive at a correct perception of the world?
not enough info in the proximal stimulus at our sensors to tell you what a distal stimulus actually is
2-D retinal image of an apple –> percept of 3-D apple
there are many possible interpretations of the proximal stimulus
different answers to this question define different schools of thought in the study of perception
What is structuralism?
goals: analyze conscious processes into basic “elements”; specify how elements become connected
Wilhelm Wundt: first psychology lab
Edward Titchener relied on introspection: analysis of one’s own conscious experience
What is the problem with structuralism?
perception is holistic, not elemental
can’t break down your conscious experience
What is Gestalt psychology?
opposed structuralism: decomposition to elementary components loses information
was a holistic approach that emphasized consciousness
goal: specify the relationship among stimuli
motto: “the whole is different than the sum of its parts”
founded by Max Wertheimer
What is constructivism?
perceiving is an active process, affected by our knowledge and experience
we must interpret ambiguous information provided by the environment
computations over internal representations yield percepts
Hermann von Helmholtz, Irvin Rock, Richard Gregory
What is the ecological approach?
we should study perception in natural settings
enough information is available in the environment to make mental calculations unnecessary
J.J. Gibson: proposed information is directly picked up from the government
What is the computational approach?
assumes the mind is an information processor that receives, stores, retrieves, transforms, and transmits information
David Marr: defined vision mathematically, using computer simulations
information processing has three levels of analysis: computational theory, representation and algorithm, and hardware implementation
What is computational theory?
what is the system doing?
e.g. what does it mean to “see” something?
What is representation and algorithm?
what is the percept? how is it being processed?
e.g. do the eyes function like cameras? is there an “inner screen” in our heads?
What is hardware implementation?
what physical “machinery” does this?
e.g. what neural circuits allow us to see?
What is the neurophysiological approach?
based on reductionism: understanding of behavior via studying the underlying biological processes
important for sensation, less effective for perception
Perception
the experiences that result from stimulation of the senses
Sensation
often identified with elementary processes that occur at the beginning of a sensory system
Perceptual Process
a sequence of steps leading from the environment to perception of a stimulus, and action with regard to the stimulus
Distal Stimulus
the stimulus “out there”, in the external environment
Proximal Stimulus
the stimulus on the receptors
in vision, this would be the image on the retina
Ciple of Transformation
stimuli and responses created by stimuli are transformed, or changed, between the distal stimulus and perception
Principle of Representation
everything a person perceives is based not on direct contact with stimuli but on representations of stimuli that are formed on the receptors and the resulting activity in the person’s nervous systems
Transduction
the transformation of environmental energy to electrical energy
Neural Processing
operations that transform electrical signals within a network of neurons or that transform the response of individual neurons
Sensory Receptors
cells specialized to respond to environmental energy, with each sensory system’s receptors specialized to respond to a specific type of energy
Cerebral Cortex
the 2-mm-thick layer that covers the surface of the brain and contains the machinery for creating perception, as well as for other functions, such as language, memory, and thinking
Visual Form Agnosia
an inability to recognize objects
Primary Receiving Area
area of the cerebral cortex that first receives most of the signals initiated by a sense’s receptors
for example, the occipital cortex is the site of the primary receiving area for vision, and the temporal lobe is the site of the primary receiving area for hearing
Knowledge
any information that the perceiver brings to a situation, such as prior experience or expectations
Bottom-Up Processing
processing that is based on the information on the receptors
also called data-based processing
Top-Down Processing
processing that starts with the analysis of high-level information, such as knowledge a person brings to a situation
also called knowledge-based processing
Stimulus-Behavior Relationship
the relationship between stimuli and behavioral responses, where behavioral responses can be perception, recognition, or action
Psychophysics
measures the relationships between the physical (stimulus) and the psychological (behavioral responses)
Grating Acuity
the narrowest spacing of a grooved surface on the skin for which orientation can be accurately judged
Stimuli-Physiology Relationship
the relationship between stimuli and physiological responses
Physiology-Behavior Relationship
relationship between physiological responses and behavioral responses
Absolute Threshold
the smallest stimulus level that can just be detected
Threshold
the minimum stimulus energy necessary for an observer to detect a stimulus
Classical Psychophysical Methods
the methods of limits, adjustment, and constant stimuli. described by Fechner, that are used for measuring thresholds
Difference Threshold
the smallest difference between two stimuli that enables us to tell the difference between them
Magnitude Estimation
a psychophysical method in which the subject assigns numbers to a stimulus that are proportional to the subjective magnitude of the stimulus
Perceived Magnitude
a perceptual measure of stimuli, such as light or sound, that indicates the magnitude of experience
Reaction Time
the time between presentation of a stimulus and the person’s reaction to it
Phenomenological Report
method of determining the relationship between stimuli and perception in which teh observer described what he or she perceives
Electromagnetic Spectrum
continuum of electromagnetic energy that extends from very-short-wavelength gamma rays to long wavelength radio waves
visible light is a narrow band within this spectrum
