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F
(1, 122)
¼
17.48,
p
<
.01, as in the case of color-naming reaction times
above. Again, participants showed slower word-naming reaction times
when hypnotized than when not hypnotized.
The total number of time-outs (response times greater than or equal to
2000ms) was calculated for each participant in each condition. Another
2 2 5 ANOVAwas carried out on thismeasure. As with color-naming
reaction times, above, the only significant effect was for hypnosis,
F
(1, 122)
¼
10.39,
p
<
.01. Table 1 shows that time-outs also increase in
the hypnotized condition compared to the nonhypnotized condition.
Total error rates.
Total errors (failures to suppress competing re-
sponses) were calculated across all incongruent Stroop trials (color-
naming no-change, color-naming change, word-naming no-change,
and word-naming change) for each individual in each condition. These
total error rates were analyzed by a 2 2 5 ANOVA. In this instance,
significant main effects were obtained both for hypnosis,
F
(1, 122)
¼
4.92,
p
<
.03; and susceptibility,
F
(1, 122)
¼
5.77,
p
<
.02. There was no
significant effect for strategy-instruction condition.
As Table 2 shows, participants made more errors when hypnotized
than when not hypnotized. High susceptible participants made more
errors than did low susceptible participants. However, these main effects
must be interpreted in light of the significant interaction effect found
Table 1
Objective Stroop Performance in Hypnotized and Nonhypnotized Conditions
Hypnosis
Measures
Time-Outs
Condition
Color-Naming
Word-Naming
Reaction
Time
Percentage
Errors
Reaction
Time
Percentage
Errors
Hypnotized 759 (169) 6.32 (7.40) 595 (158) 3.95 (7.61) 2.05 (4.01)
Nonhypnotized 723 (143) 6.23 (5.99) 553 (137) 3.08 (5.45) 1.20 (2.12)
Table 2
Percentage of Total Errors for High and Low Susceptibles in Hypnotized and
Nonhypnotized Conditions
Susceptibility
Condition
Row Totals
Hypnotized
Nonhypnotized
High
6.42 (6.03)
4.87 (3.95)
5.65 (5.14)
Low
4.20 (3.58)
4.08 (3.01)
4.14 (3.08)
Column Totals
5.31 (4.93)
4.47 (3.52)
240
GRAHAM A. JAMIESON
AND
PETER W. SHEEHAN
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