Sensation and Perception
Chapter 1 Sensation and Perception
Without your senses, the world would simply not exist for you. The philosopher Tomas Hobbes
recognized this fact in 1651 when he wrote: there is no conception in man’s mind which had not at
first, totally or by parts, been begotten upon the organs of sense.
The Greek philosopher Protagoras stated the same position around 450 B.C. when he said: man is
nothing but a bundle of sensations.
Your world is what your senses tell you. The limitation of your senses set the boundaries of your
conscious existence.
The ease with which we use our senses masks the fact that perception is an extremely sophisticated
activity of the brain.
Perception calls on stores of memory data. It requires subtle classifications, comparison and myriad
decisions before any of the data in our senses become our conscious awareness of what is out there.
Contrary to what you may think, the eyes do not see. There are many individuals who have perfectly
functioning eyes yet have injuries in those parts of the brain that receive and interpret messages
from the eyes.
Sensation and perception are some of the many complex processes that occur in the continuing of
individual behavior. There is no clear line between perception and many other behavioral activities.
No sensory impression gives direct knowledge of the outside world; rather, such knowledge of the
outside world is the end product of many processes.
Yet sensory data are not always reliable. Sometimes they can be degraded or not completely
available.
Sensory stimulation provides the data for our hypotheses about the nature of the external world.
And it is these hypotheses that form our perceptions of our world.
It is amazing to discover the degree to which our conscious experience of the world can differ from
the physical reality (coals pantheon in athene).
Such distortions, in the form of disagreements between percept and reality, are quite common. We
call them illusions, and they occur in predictable circumstances for normal observers. The term
illusion is drawn from the Latin root illudere, meaning ‘to mock’, and in a sense illusions do mock us
for our unthinking reliance on the validity of our sensory impressions. Every sensory modality is
subject to distortions, illusions, and systematical errors that misrepresent the outside environment
to our consciousness.
Aspects of the perceptual process
Alexander Bain wrote the first English textbook on psychology in 1855, it was titled ‘The senses and
the intellect’, with the most extensive coverage reserved for sensory and perceptual functions. The
major portion of both the theorizing and the empirical work produced by Wilhelm Wund, who is
generally credited with the founding of experimental psychology, was oriented toward sensation and
perception.
The study of sensation, or sensory processing, is concerned with the first contact between the
organism and the environment. Thus, someone studying sensation might look at the way in which
electromagnetic radiation (light) is registered by the eye.
, Someone who is interested in the study of perception is interested in our conscious experience of
objects and object relationships. For instance, the sensory question might be “How bright does the
target appear to be?” whereas the perceptual questions would be “Can you identify that object?”
and “Where is it?”. In a more global sense, those who study perception are interested in how we
form a conscious representation of the outside environment and in the accuracy of that
representation.
Cognition is a term used to define a very active field of inquiry in contemporary psychology.
Cognition tends to be somewhere between the areas that were traditionally called perception and
learning, and it incorporates elements of both.
Information processing is a relatively general term but is used to emphasize the whole process that
finally leads to identification and interpretation of stimuli. This approach focuses on how information
about the external world is operated on to produce our conscious percepts and guide our actions.
Information processing is typically assumed to include a registration or sensory phase, an
interpretation or perceptual phase and a memoric or cognitive phase.
It relies on a levels-of-processing analysis in which each stage of sensory processing, from
the first registration of the stimulus on the receptor to the final conscious representation entered
into memory, is systematically analyzed.
Theories of perception
One important approach may be called biological reductionism. It is based on the presumption that
for any given aspect of the observer’s sensation there is a corresponding biological event. According
to this approach, the main goal of the perceptual researcher is to isolate the underlying physiological
mechanisms.
Modularity of perception is the view which was first offered by Jerry Fodor (1983) and it views the
mind as a set of distinct units or modules, each of which is complete in itself and has a specific
function with dedicated neural hardware. This allows the processing to be quick but does not require
any conscious intervention. Perception, made up of the output of many modules, is then passed on
to higher centers where cognitive processes can come into play.
Direct perception begins with the premise that all the information needed to form the conscious
percept is available in the stimuli that reach our receptors.
Perceptual invariants are fixed properties of the stimulus even though the observer may be
moving or changing viewpoints, causing continuous changes in the optical image that reaches the
eye. This stimulus information is automatically extracted by the perceptual system because it is
relevant to survival.
Invariants provide information about affordances, which are action possibilities afforded or available
to the observer, such as picking up an object, going around it, and so forth.
The label of direct perception was given to such theories by JJ Gibson, who argued that this
information is directly available to the perceiver and is not based on any higher-level cognitive
processing or computation.
The computational theories differs from direct perception in that it described the piecing together of
information based on some simple dimensions in the stimulus, such as boundaries and edges, line
endings, particular patterns where stimuli meet. This process of interpretation or synthesis is
believed to require a number of computations and several stages of analysis that can be specified as
mathematical equations or steps in a computer program.
Chapter 1 Sensation and Perception
Without your senses, the world would simply not exist for you. The philosopher Tomas Hobbes
recognized this fact in 1651 when he wrote: there is no conception in man’s mind which had not at
first, totally or by parts, been begotten upon the organs of sense.
The Greek philosopher Protagoras stated the same position around 450 B.C. when he said: man is
nothing but a bundle of sensations.
Your world is what your senses tell you. The limitation of your senses set the boundaries of your
conscious existence.
The ease with which we use our senses masks the fact that perception is an extremely sophisticated
activity of the brain.
Perception calls on stores of memory data. It requires subtle classifications, comparison and myriad
decisions before any of the data in our senses become our conscious awareness of what is out there.
Contrary to what you may think, the eyes do not see. There are many individuals who have perfectly
functioning eyes yet have injuries in those parts of the brain that receive and interpret messages
from the eyes.
Sensation and perception are some of the many complex processes that occur in the continuing of
individual behavior. There is no clear line between perception and many other behavioral activities.
No sensory impression gives direct knowledge of the outside world; rather, such knowledge of the
outside world is the end product of many processes.
Yet sensory data are not always reliable. Sometimes they can be degraded or not completely
available.
Sensory stimulation provides the data for our hypotheses about the nature of the external world.
And it is these hypotheses that form our perceptions of our world.
It is amazing to discover the degree to which our conscious experience of the world can differ from
the physical reality (coals pantheon in athene).
Such distortions, in the form of disagreements between percept and reality, are quite common. We
call them illusions, and they occur in predictable circumstances for normal observers. The term
illusion is drawn from the Latin root illudere, meaning ‘to mock’, and in a sense illusions do mock us
for our unthinking reliance on the validity of our sensory impressions. Every sensory modality is
subject to distortions, illusions, and systematical errors that misrepresent the outside environment
to our consciousness.
Aspects of the perceptual process
Alexander Bain wrote the first English textbook on psychology in 1855, it was titled ‘The senses and
the intellect’, with the most extensive coverage reserved for sensory and perceptual functions. The
major portion of both the theorizing and the empirical work produced by Wilhelm Wund, who is
generally credited with the founding of experimental psychology, was oriented toward sensation and
perception.
The study of sensation, or sensory processing, is concerned with the first contact between the
organism and the environment. Thus, someone studying sensation might look at the way in which
electromagnetic radiation (light) is registered by the eye.
, Someone who is interested in the study of perception is interested in our conscious experience of
objects and object relationships. For instance, the sensory question might be “How bright does the
target appear to be?” whereas the perceptual questions would be “Can you identify that object?”
and “Where is it?”. In a more global sense, those who study perception are interested in how we
form a conscious representation of the outside environment and in the accuracy of that
representation.
Cognition is a term used to define a very active field of inquiry in contemporary psychology.
Cognition tends to be somewhere between the areas that were traditionally called perception and
learning, and it incorporates elements of both.
Information processing is a relatively general term but is used to emphasize the whole process that
finally leads to identification and interpretation of stimuli. This approach focuses on how information
about the external world is operated on to produce our conscious percepts and guide our actions.
Information processing is typically assumed to include a registration or sensory phase, an
interpretation or perceptual phase and a memoric or cognitive phase.
It relies on a levels-of-processing analysis in which each stage of sensory processing, from
the first registration of the stimulus on the receptor to the final conscious representation entered
into memory, is systematically analyzed.
Theories of perception
One important approach may be called biological reductionism. It is based on the presumption that
for any given aspect of the observer’s sensation there is a corresponding biological event. According
to this approach, the main goal of the perceptual researcher is to isolate the underlying physiological
mechanisms.
Modularity of perception is the view which was first offered by Jerry Fodor (1983) and it views the
mind as a set of distinct units or modules, each of which is complete in itself and has a specific
function with dedicated neural hardware. This allows the processing to be quick but does not require
any conscious intervention. Perception, made up of the output of many modules, is then passed on
to higher centers where cognitive processes can come into play.
Direct perception begins with the premise that all the information needed to form the conscious
percept is available in the stimuli that reach our receptors.
Perceptual invariants are fixed properties of the stimulus even though the observer may be
moving or changing viewpoints, causing continuous changes in the optical image that reaches the
eye. This stimulus information is automatically extracted by the perceptual system because it is
relevant to survival.
Invariants provide information about affordances, which are action possibilities afforded or available
to the observer, such as picking up an object, going around it, and so forth.
The label of direct perception was given to such theories by JJ Gibson, who argued that this
information is directly available to the perceiver and is not based on any higher-level cognitive
processing or computation.
The computational theories differs from direct perception in that it described the piecing together of
information based on some simple dimensions in the stimulus, such as boundaries and edges, line
endings, particular patterns where stimuli meet. This process of interpretation or synthesis is
believed to require a number of computations and several stages of analysis that can be specified as
mathematical equations or steps in a computer program.
