SUBLIMINAL PERCEPTION
SUBLIMINAL PERCEPTION
|
|
A subliminal message is a signal or message
embedded in another object, designed to pass below the normal limits of
perception. These messages are indiscernible by the conscious mind, but
allegedly affect the subconscious or deeper mind. Subliminal techniques have
occasionally been used in advertising and propaganda; the purpose,
effectiveness and frequency of such techniques is debated. Subliminal perception occurs whenever stimuli
presented below the threshold or limen for awareness are found to influence
thoughts, feelings, or actions. The term subliminal perception was originally
used to describe situations in which weak stimuli were perceived without
awareness. In recent years, the term has been applied more generally to
describe any situation in which unnoticed stimuli are perceived.
CONCEPT
The concept of
subliminal perception is of considerable interest because it suggests that
peoples' thoughts, feelings and actions are influenced by stimuli that are
perceived without any awareness of perceiving. This interest was reflected in
some of the earliest psychological studies conducted during the late 1800s and
early 1900s. In these early studies, people were simply asked whether or not
they were aware of perceiving. For example, visual stimuli such as letters,
digits, or geometric figures were presented at such a distance from observers
that they claimed either not to see anything at all or to see nothing more than
blurred dots. Likewise, auditory stimuli such as the names of letters were
whispered so faintly that observers claimed that they were unable to hear any
sound whatsoever. To test whether these visual or auditory stimuli may have
been perceived despite the statements to the contrary, the observers were asked
to make guesses regarding the stimuli.
Example: If half the stimuli were letters and half
the stimuli were digits, the observers may have been asked to guess whether a
letter or a digit had been presented. The consistent result found in these
early studies was that the observers' guesses regarding the stimuli were more
correct than would be expected on the basis of chance guessing. In other words,
despite the observers' statements indicating that they were unaware of
perceiving the stimuli, their guesses indicated that they did in fact perceive
sufficient information to make accurate guesses regarding the stimuli. Over the
years, there have been literally hundreds of studies following a similar
format. Taken together, these studies show that considerable information
capable of informing decisions and guiding actions is perceived even when
observers do not experience any awareness of perceiving.
Another way in which
subliminal perception has been demonstrated in controlled laboratory studies is
by showing that stimuli can be perceived even when they are presented under
conditions that make it difficult if not impossible to distinguish one stimulus
from another stimulus. The classic studies were conducted in the 1970s by the
British psychologist Anthony Marcel. These experiments were based on previous
findings indicating that a decision regarding a stimulus is facilitated or
primed when the stimulus follows a related stimulus. For example, if an
observer is asked to classify a letter string as either a word (e.g., doctor,
bread) or a nonword (e.g., tocdor, dreab), a letter string such as the
word doctor will be classified as a word faster when it follows a
semantically related word (e.g., nurse) than when it follows a semantically
non-related word (e.g., butter). Marcel found that words facilitated or
primed subsequent word/nonword decisions to letter strings even when the words
were presented under conditions that made it difficult if not impossible for
the observers to distinguish when the words were present from when the words
were absent. Since the time of Marcel's original experiments, there have been
many other studies that have used similar methods. Not only have these studies
confirmed Marcel's original findings, but they have shown that other stimuli
such as pictures, faces, and spoken words can also facilitate subsequent
decisions when they are presented under conditions that make it difficult to
discriminate one stimulus from another stimulus. Although questions have been
raised regarding whether the observers in these studies were completely unable
to discriminate one stimulus from another stimulus, the one firm conclusion
that can be made on the basis of these studies is that considerable information
is perceived even when observers experience little or no awareness of
perceiving as indicated by their difficulty in discriminating one stimulus from
another stimulus.
Examples of subliminal
perception are found in studies of patients with neurological damage. A
striking characteristic of a number of neurological syndromes is that patients
claim not to see particular stimuli but nevertheless respond on the basis of
information conveyed by these stimuli. One example is a syndrome called blindsight.
Patients with blindsight have damage to the primary visual cortex. As a result
of this damage, they are often unaware of perceiving stimuli within a
restricted area of their visual field. For example, if the visual field is
thought of as consisting of four quadrants, a blindsight patient may have
normal vision for stimuli presented in three of the quadrants but be completely
unaware of stimuli presented in the fourth quadrant. However, even though these
patients may claim not to see stimuli located within the "blind"
quadrant, they are still able to guess the size, shape or orientation of the
stimuli that they claim not to see. Another neurological syndrome in which
subliminal perception occurs is prosopagnosia or face agnosia. Patients with
prosopagnosia are unable to recognize familiar faces. Although they may be
aware that they are looking at a person's face, they are unable to say who the
person may be. Thus, prosapagnosics have no awareness of perceiving any
information regarding whose face they may be viewing. However, despite this
absence of awareness, some patients with prosapagnosia are able to choose which
of two names goes with each familiar face that they claim not to be able to
recognize.
Comments
Post a Comment