In the face of all this, what makes us think we have representative people giving us representative samples of dream reports in numbers that are large enough to give us confidence that we have solid findings?
As far as the representativeness of the people, the many studies of
high and low dream recallers can provide us with an answer. There are only
small differences -- if any -- between high and low dream recallers on a
variety of personality and cognitive tests. It therefore follows that those
who contribute dream reports are a representative sample of people for every
personality and cognitive test devised so far by psychologists. Furthermore,
there is evidence that high recallers differ primarily in their interest in
dreams and their motivation to recall them, which are factors restricted to
the issue of dreams, and therefore not a challenge to the general
representativeness of the people who report dreams. Put another way,
"interest" and "motivation" concerning dreams do not correlate with
personality and cognitive variables.
Turning now to the representativeness of the dream reports that these
representative people give us, there are several steps to the argument, most
of which are based on dream reports collected from awakenings throughout the
night in sleep laboratories.
1. We know from studies using dreams collected in the laboratory that they do not differ very much, if at all, from the reports of dreams at home from the same subjects.
2. We know from studies in the sleep lab that dream reports from early in the night do not differ much, if at all, from dreams collected later in the sleep period, which is essential to the next point.
3. We have reason to believe that the dreams we recall upon awakening in the morning are most likely to be the ones we just dreamed, but this poses no problem because of the previous finding, that the last dream reports of a sleep period to not differ from those earlier in the night.
4. We know from studies of reports collected from awakenings throughout the night in sleep labs that "recency" and "length" are the main factors in determining which of the earlier reported dreams are recalled once again in the morning. The "dramatic intensity" of the report is a third factor, but a study in which subjects immediately telephoned a report when they recalled a dream during the day showed that minor cues in our environment can trigger the recall of very mundane (i.e., those of low "dramatic intensity") dreams, thereby balancing the influence of dramatic intensity on morning recall. We also know that dramatic intensity is not a big influence on dream recall because our normative studies show that a majority of dream reports do not contain the aggression, sexuality, or bizarreness that supposedly make dreams "dramatic." When all is said and done, then, the laboratory studies, the telephone study, and our norms give us confidence that recency, length, and everyday cues are leading us to a representative sample of dream life.
For individuals, we used dream series where we had findings with anywhere
from 150 to nearly 1000 dream reports, then compared the overall findings for
each series with the results for subsamples of 25, 50, 75, and 100 dream
reports, and found we could match the overall findings within a few
percentage points when the subsample reached 75 and 100.
For groups, we first compared the overall findings in Hall and Van De
Castle's original normative sample of 500 male dream reports from 100
individuals with the results for subsamples of 25, 50, 75, 100, and 125, and
250, and found a similarity to the overall norms within a few percentage
points with subsamples of 100 and 125. Then we compared 100 Most Recent
Dreams from 100 women college students at the University of California, Santa
Cruz, in the early 1990s with Hall and Van De Castle's normative findings on
500 dream reports from 100 women, and found that the overall results in our
percentages and indexes were almost exactly the same for both samples.
Click here to see a table with the
actual data from our subset analysis of the Male Norms.
Why do we believe that subjects are giving us full and honest reports? There
are three answers. First, almost all of our subjects provide dream reports
anonymously, reducing any tendency to misreport. Second, people express a
lack of personal responsibility for their dreams, which leaves them quite
willing to report whatever they experience. For most people, dreams are
something that happen to them, an experience, so they do not see them as a
reflection on their self-
As far as sample sizes, they have been too small in the past, but by drawing
many subsamples of varying sizes from large samples where the overall results
are known, we now know that it takes 75 to 100 reports to sample anindividual's
dream life adequately and 100 to 125 for a sound comparison of a group's dream
reports to our norms.
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