CHANGES IN PERCEPTION FOLLOWING YOGA PRACTICE
Following yoga practices offers changes in perception
Title: CHANGES IN PERCEPTION FOLLOWING YOGA PRACTICE
Author: Manoj Dash,BHMS,DYT,Ph.D.
Article:
Perception is sensation with added complexity due to factors
such as memories and emotions. Yoga practice influences
perception in three ways: (1) by increasing perceptual
sensitivity, (2) by selectively `shutting out’ undesirable
stimuli, and (3) by changing distorted perception, which occurs
in schizophrenia. Practicing yoga improved auditory and visual
perception, by increasing sensitivity to various characteristics
of the stimuli (e.g., intensity, frequency). Also,
electrophysiological studies using evoked potentials have shown
that during yoga practice the transmission of sensory
information is facilitated. These studies suggest several
applications of yoga practice, in activities ranging from
aviation to art. Interestingly, other studies suggest that yoga
practice can also help to `shut off’ undesirable external
stimuli, which is possibly due to cortical feedback connections
to the sensory pathway. It is also possible that through changes
in cognitive factors yoga influences perception, so that even
though the stimulus is `sensed’ it is not disturbing. This
concept has been studied using yoga to help persons with chronic
pain to willfully ignore it. Finally, preliminary studies have
shown that yoga practice may modify distorted perception in
conditions such as schizophrenia. Hence, there is sufficient
research to support the idea that yoga practice influences
perception in different ways, with varied applications.
Perception is the process of interpretation, organization, and
elaborating the `raw materials’ of sensation (1). Sensation
involves sensory receptors and pathways, whereas perception is a
cognitive process. The actual perception of a sensation depends
on factors such as what has been learned, memories, and
emotions. It is also important to remember that while perception
usually refers to sensory stimuli, this definition can be
extended to include the perception of situations. Recordings of
middle latency auditory evoked potentials (AEP-MLRs) have shown
that the practice of ujjayi pranayama modifies the AEP-MLRs
components in two ways. A specific component (the Na wave) has
reduced latency and increased amplitude during pranayama
practice (2). These results suggest that this practice
facilitates the processing of auditory information at
mesencephalic and diencephalic levels. A similar result was also
seen during the practice of meditation on the syllable Om (3),
where subjects who had more than ten years of meditation
experience, showed an increase in the Na wave amplitude and a
decrease in its’ latency while mentally repeating (Om). No such
effect was seen when the same subjects mentally repeated `one’,
during a control session, for comparison. These
electrophysiological data are corroborated by neuropsychological
studies. Previous studies on meditation have shown significant
changes in perception, attention and cognition (4). Brown and
Engler in 1980 (5), reported that meditators were found to be
more sensitive to subtle aspects of color and shading of the
Rorschach test inkblots, than they had been before meditation.
Two studies on the Critical Flicker Fusion Frequency have shown
that perceptual sensitivity is not restricted to subtle aspects
of the stimulus alone, as detection of a high frequency
flickering stimulus was found to improve following yoga training
(6,7). A study on the degree of a visual geometric illusion,
based on Müller-Lyer lines showed that a combination of focusing
and defocusing yoga visual exercises reduces optical illusion
more than focusing alone (8). These studies were conducted on
adult subjects with varying durations of yoga training. It was
reported in a recent study on Critical Flicker Fusion Frequency
and optical illusion on children who practiced yoga for a
shorter duration of 10 days that there was also a significant
improvement following the practice of yoga (9). To perceive an
optical illusion with minimal error and for accurate depth
perception the spatial component of visual perception is
necessary (10). The decrease in the degree of optical illusion
perceived over a short period would be mainly due to cognitive
judgmental factors, but not retinal or cortical factors as
generally understood (11). The cognitive judgmental factors
involve the way in which the subject interprets incoming visual
information based on experience, hypothesis and strategies of
judgment. Hence the training through yoga to focus and defocus
might have influenced the cognitive judgmental factors of the
subjects, to significantly reduce the degree of optical illusion
perceived. Critical flicker fusion frequency (CFF), on the other
hand, assesses the temporal component of perception of a visual
stimulus (12). The increase in CFF following yoga could be
attributed to the effects of yoga reducing physiological signs
of stress, as CFF was found to be lower during specific
stressors, such as food and water deprivation (13). This showed
that both spatial and temporal components of visual perception
are modified following yoga practices. Hence the
electrophysiological data as well as the visual,
neuropsychological studies cited above have shown that yoga
practice improves diverse aspects of auditory and visual stimuli
in normal volunteers. An interesting difference in auditory
perception (based on AEP-MLRs) were also seen in congenitally
blind children (14) and adults (15) compared to those with
normal sight. The changes suggested improved auditory perception
which could be a compensatory mechanism of auditory sensation in
the presence of poor vision. The effect of yoga has been
observed on the perception of situations. Examples of a change
in the way persons perceive situations was observed in two
separate groups of subjects. A study on 69 aged persons (above
60 years of age), staying in an old age home, showed that after
6 months of yoga practice there was a reduction in their
feelings of depression, based on the Geriatric Depression Scale
suggesting a favorable change in the wy they perceived their
circumstances (16). Another study on ten patients with breast
cancer (stage 2 and 3), showed reduction in depression and
anxiety (using Beck’s Depression Scale, Spielberger’s State and
Trait Anxiety Inventory), after practicing yoga for 6 months.
Hence yoga can probably have positive effects on both sensory
perception and on the way situations or circumstances are
perceived (17). Finally, there may be more ways of perceiving
the world than we know about. As the renowned sensory
neurophysiologist, Vernon B. Mountacastle said: “Each of us
lives within…..the prison of his own brain. Projecting from it
are millions of fragile sensory nerve fibers, in groups uniquely
adapted to sample the energetic states of the world around us:
heat, light, force, and chemical composition. That is all we
ever know of it directly; all else is logical inference” (18).
Yoga may allow an advanced practitioner to develop `siddhis’ or
special powers, which may hence allow such a person to have a
different, possibly `expanded’ perception of the world.
About the author:
I am a Doctor, doing my Ph.D.in Yoga. My topic of interest is to
conduct Yoga Retreat, take class for Yoga Teacher and Medical
professionals for in depth Research findings, and also Interest
to conduct research in various field of yoga, both experimental
and theoretical. I have been Traveling to all EUROPIAN
countries. My contact: yoga4all@india.com My web page:
http://www.geocities.com/manojrieneke/Research.html
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