Using QEEG to evaluate Media effects
Americans watch television, listen to the radio, and
read newspapers and magazines an average of 8 hours and 3 min a
day (Mendes, 1992). More time is spent attending to media than
sleeping. Of this time, 3 hours and 48 min are devoted solely to
television watching. The amount of time attending to media has
risen 40 min in 20 years with little possibility of curtailing in
the future, despite the fact that heavy television watching is
correlated with lower income, smoking, increased tiredness, and
reduced sexual activity (Forrest & Ryan, 1977).
Film and television are ubiquitous in our culture, yet
very little attention has been given to psychophysiological
studies of cinematic media. Films consist of selective scenes
organized in such as way as to construe meaning and purpose into
an otherwise arbitrary succession of events, yet while watching a
narrative one is usually not struck by it artificiality. In fact,
individuals use the metaphors and plots, even the dialogue, from
film and television programs in constructing his or her own self-
narrative. According to Blaukopf (1990), the "mediasphere" is
permeated with concepts and relationships that should be
investigated further, or, at all. The effect of picture
definition, the influence of flicker rate on concentration and
fatigue, the influence of visual angle and viewing distance on
perception, to name a few, are important variables that can
easily be addressed with quantitative EEG.
The concept of interest is also a bit of an enigma.
Interest drives much of our actions, but few scientist study it
outright. A behavioral measure of interest was used to analyze
the second 1992 Presidential debate, but no papers were
forthcoming from this data. Hidi (1990) speculates that cognitive
interest differs from conscious attention in both psychological
and physiological processes, but again no one has yet followed up
this premise.
Cinematographic techniques have been developed with one
purpose in mind: to attract our interest and attention to the
silver screen and keep it there. Physiological responses to
camera edits, zooms, and the like, have been investigated by
Reeves et al. (1985) and Lang (1990), but such measures
lack functional resolution. The use of EEG to evaluate specific
techniques is one application of this research. Continuous values
of attentional synchrony or alpha amplitude may be used to determine when a edit or
zoom promotes a message or narrative content and when it fades in
usefulness. Quantitative EEG can be used as to intervene in the
creation process. For instance, when should music be added to a
film to enhance a mood or accentuate a dramatic point? Whenever
attentional synchrony in the right hemisphere is ebbing.
Interest measures
Television viewing time correlates with subjective
interest in a program, but this measure, as many behavioral and
subjective measures, requires long length of time, lasting
anywhere from minutes to half-hours (Olney, Holbrook, & Batra,
1991). One advantage of attentional synchrony and alpha amplitude is that both
psychophysiological measures can be calculated for very brief
durations (e.g., 125 ms). attentional synchrony values showed significant
correlations with behavioral ratings across a film in 75 percent
of those examined. Mean alpha magnitude correlated with even
fewer films. Yet it's likely that for short segments of time
(e.g., 2 s) the behavioral measure was the least reliable index
of interest. Validation of this assumption will require further
testing.
Besides temporal resolution, EEG measures have many
advantages over behavioral or subjective measures. Behavioral
tasks such as secondary tasks have also been criticized for being
unreliable, intrusive, and insensitive to rapid or moderate
psychological or physiological changes (Kerr, 1973; Kramer,
1991). Secondary tasks, a common index of attention, can elevate
task demand artificially (Kramer, 1991). Behavioral measures
require active, overt participation by the subject whereas EEG
can be acquired during conditions of very low involvement. Unlike
subjective measures, cortical responses do not have to pass
through the verbal system nor are subjects forced to categorize
mental states or adopt arbitrary conventions to respond
(Rothschild & Thorson, 1983).
Methodological issues
The rapid advance of desktop technology has been a
dangerous boon for EEG research in particular and for science in
general. Relatively inexpensive but sophisticated acquisition and
analysis technology has created a surge in EEG applications and
users and along with it a proliferation of incompatible results.
Some of the advantages of quantitative EEG -- reliability,
portability, sensitivity, and cheapness -- has in some ways
helped to undermine the credibility of this assessment tool. The
lack of standards in basic areas of quantitative EEG research
(e.g., electrode number, bandwidth) continues to confound the
effectiveness of this tool and limited its acceptance and what
should be routine implementation in many circumstances. To
further the creation of standards, a minimum of eight recording
electrodes was recommended for neuropsychological research, a
suggestion that can be implemented immediately. This review has
compared the various approaches and has incorporated this
information into the following design and analysis. With this in
mind, it is clear that quantitative topographic EEG holds great
potential for the study of higher cognitive functions, possibly
more so than any other approach in common use today.
Future avenues of research
Future research should concentrate on two issues: 1)
analysis of EEG correlates of subjective interest in other
frequency bands and for other stimuli (e.g., music, paintings),
and 2) further investigation of attentional synchrony. In terms
of frequency bands, the traditional alpha frequency may consist
of independently rhythms that are better investigated in
isolation. For instance, Klimesch, Pfurtscheller, & Schimke
(1992) reported that the lower alpha range (8-10 Hz) reflects
arousal and alertness whereas the upper alpha range (10-12 Hz)
reflects task-related cognitive processes and selective
attention. In terms of the attentional synchrony, other formulations of attentional synchrony may be
more sensitive to group attention and processing. For example,
whether attentional synchrony increases over time may reflect interest of monotony
better than mean values. The model of attentional inertia would
predict that attentional synchrony would decline across time once interest in a
task or stimulus is engaged. Also, other derivation unrelated to
between-subject standard deviation may prove to be better indices
of attentional synchrony. Quantification of ERD-PRS cycles in continuous EEG may
prove to be a very useful approach to measuring attentional synchrony.
Concept of synchrony
The concept of psychological or psychosocial synchrony
is intriguing. Behavioral synchrony is a prominent development in
the relationship between mother and infant (Bernieri et
al., 1988). Frecska and Kulcsar (1989) argued that certain
healing rituals are effective because they produce a deep
psychobiological synchrony between adults. The ritual experience
which includes trance, dance, fellowship, and rhythms, may have
as its goal a form of attentional synchrony, one that unites
individuals in harmonious fellowship and oneness. In this light,
cinema may serve the same role that ritual in pre-industrial age
once served. It unites minds, if only for an hour or two, and in
so doing, invokes wholeness.
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