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current knowledge about the legislature, measured at T2 only. The maximum score was 16 and the average score for all respondents was 8.7, or an average score of 55% correct in terms of current legislative activities.
Watching the television series led to average knowledge scores of 9.84;
the non-viewers in the experiment scored 7.64 (Table 4).
In addition to the
statistical significance of this difference, it is important to note that
Again, to look at the possibility that exposure improved moreso the
know ledge levels of those already more knowledgeable, we compared the results
on this index between black and white youngsters. Within the control group,
there was no particular difference in level of knowledge between blacks and
whites. However, the white youngsters in the experimental group correctly
answered two more questions on the average than the black youngsters who had seen the series. In terms of the kind of differential learning rate being discussed, the white viewers answered correctly 2 1/2 more questions per person than the white non-viewers, whereas the black viewers answered correctly one more question than the black non-viewers.
The final measure of knowledge dealt with the individual's understanding of how the legislature tends to work. For example, what do amendments do, the importance of committee hearings, the attention given by legislators to floor activity. The maximum score on this index could be 23. The average score for the viewers was 16.36. This compared to an average score of 12.31 for the non-viewers or control groups. Obviously, watching the series increased information at put the nature of the legislative process. Again, the overall level of effect was to increase by 1/3 the available knowledge
among all the viewers.
We looked again for any evidence that such knowledge increments might
be a differential function of the original knowledge level of the viewer,
and that this in turn could be related to one's social background.
respondents in both the experimental and control groups scored significantly higher than their black peers. The difference in knowledge between the white viewers and non-viewers was four units; the difference between black viewers and non-viewers was three units. Although this is a smaller gap, it repre
sents fully 25% more learning among the presumably more advantaged learning
For all these knowledge gap comparisons, one caution must be explicitly
expressed. Social class differences are con founded with racial difference.
Lower class whites did not learn about politics at a different rate than lower class blacks, although the former were more knowledgeable to begin with. The source of the "gap" was found primarily in the amount of the learning done by middle-class whites, for whom no sizable black counterpart existed for comparison pruposes.
For each type of cognitive information assessed, watching a political series on public television created a substantial growth in political know
ledge. This was so whether one was asking if the youngsters had learned
about the political process in general, about current legislative activities
in particular, or about who the main persons in legislative activities are.
Note an Initial Experimental-Control Group Differences :
On several dependent variables, the experimental and control groups were
not equivalent at the outset of the study. Considering experimental condition as an ordinal variable (non-viewers = 0, viewers = 1), there was a slight
correlation between treatment and initial scores on five variables listed
below. A partialling technique was used to eliminate this initial relation
ship from the post-viewing analyses. Partial correlations were computed between experimental treatment and the T2 scores on each variable, controlling
for the ti correlation. The initial associations were also partialled out of
at T2 become marginal when Tl scores are taken into account; the post-viewing association with treatment drops from +. 12 to +.06. These adjusted figures indicate that the programs had little impact on the efficacy variable.
Basic Political knowledge. The slight Tl relationship does not reduce
the T2 correlation of +.27.
Thus, the large post-viewing difference in basic
knowledge appears to be due mainly to the experimental treatment.
National News Watching. Controlling for the original association, the null T2 correlation rises to +.06. However, the adjusted T3 correlation is still negligibly negative. It is clear that the program had no influence over television news viewing, even when the greater initial viewing in the
control group is considered.
Talking with Friends.
The originally positive relationship slightly
attenuates the raw T2 and T3 associations, but each remains significant.
Reading Legislature News. Again, the T2 and T3 correlations with ex
perimental treatment are slightly reduced.
The delayed measure still shows
a significant experimental-control group difference.
Interactions Between Treatment and Subject Characteristics
This section examines the interactions between the experimental treatment and certain antecedent variables, including demographics, academic ability, mass media exposure, interpersonal communication, and political orientations. These data are described with correlation coefficients computed be
tween treatment condition (non-viewers = 0, viewers = 1) and the dependent variables, at each of two levels of an antecedent characteristic. The two levels were created from either nominal classifications, e.g., male vs. female, or by dividing the antecedent variable at the median, e.g., knowledgeable vs. less knowledgeable. This procedure provides a simple descriptive
statistic which assesses the relative magnitude of the conditional effect of
classroom viewing on various dependent measures at both the second and third
testing sessions. The first column in Table 5a gives the correlation coeffi
cients across the overall sample. This statistic parallels the ANOVA main
Social Class: working = laborer, operative, service, craftsman, forman;
middle = sales, clerical, professional, technical,