Ubicación de la planta

This scale was comprised of eleven variables. Six out of the eleven variables showed main effects and three-way interactions between group*treatment*time were found for the visual sensitivity and impaired memory variables.

Visual sensitivity: the group * treatment * time interaction for visual sensitivity was F2,9o=

3.36, p<0.05. Post-hoc independent samples t-tests (post-pre drink) showed a difference in change scores between augmented and depleted current users [t3o= -2.03, p<0.05]. The

current users tended to show reduced visual sensitivity following depletion and increased visual sensitivity following augmentation. There were no significant differences between the depleted and augmented sub-groups in the ex-user and non-user populations.

Impaired memory: there was a three-way interaction between group*treatment*time for ratings of impaired memory [F2,9o= 3.90, p<0.05]. Post-hoc independent samples t-tests

(post minus pre-drink) showed a significant difference in change scores between augmented and depleted ex-users [t3o= -2.31, p<0.05]. Ex-users showed reduced ratings

o f memory impairment following depletion but little change following augmentation. It should be noted that the pre-drink scores (and standard deviations) for ex-users given the depleted drink were higher than those o f the augmented group before the pharmacological manipulation. This pre-treatment difference accounts for the interaction effect as there were no significant differences between current users and controls given the augmented

and depleted drinks. There was also a main efifect o f time [Fi,9o= 7.85, p<0.01] whereby

participants generally rated higher memory impairment scores pre-drink compared with post-drink, regardless o f which drink they were given.

Nausea: there was a main efifect o f treatment [Fi,9o= 10.23 p<0.005] whereby those in the

augmented condition had higher nausea ratings than those in the depleted condition. The mean score for the depleted condition was about 13 whereas those in the augmented condition scored 23. The main efifect o f time [Fi,9o= 30.13, p<0.001] showed, as expected,

that all groups had higher nausea ratings post-drink than pre-drink.

Irritability: there was main efifect o f treatment [Fi.9o= 4.27, p<0.05]. Depleted groups

were less irritable than augmented groups. Depleted groups rated a mean o f 17.15 (15.21) whereas augmented groups rated a mean o f 24.21 (17.89).

Depression and headache: on 2 scales there was a main efifect o f time: depression [Fi,90=4.84, p<0.05] and headache [Fi,9o=15.87, p<0.001]. AH groups rated lower depression post-drink than pre-drink, but had higher headache scores.

Shaking: there were pre-drink group differences [F2,93=5.19, p<0.01]. Post-hoc tests showed that ex-users had less pre-drink shaking than current users (p<0.01) and controls (p=0.05). When pre-drink scores were covaried, there were no significant group or treatment effects on post-drink scores.

There were no significant effects on the other scales (Table 3.22, Appendix III).

3. BETWEEN-SUBJECTS MEASURE: self-referent encoding

The proportion o f adjectives recalled did not differ between participants who took the depleted drink and those who took the augmented drink. Therefore, type o f drink taken was not used as a variable in subsequent analysis. As seen in Figure 3.7, four sets o f proportional scores were calculated by dividing:

(i) the number o f ‘self-positive’ adjectives recalled by the number o f ‘positive’ adjectives rated by the participant as applying to oneself

(ii) the number o f ‘self-negative’ adjectives recalled by the number of ‘negative’ adjectives rated by the participant as applying to oneself

(iii) the number o f ‘other-positive’ adjectives recalled by the number of ‘positive’ adjectives rated by the participant as applying to an unfamiliar ‘other’ person (iv) the number o f ‘other-negative’ adjectives recalled by the number of ‘negative’

adjectives rated by the participant as applying to an unfamiliar ‘other ‘ person.

Figure 3.7. Formula for calculating proportional scores on self-referent encoding task.

Self/other ‘positive’ Self/other ‘negative’

N recalled +ve yes/ -ve no N recalled -ve yes/ +ve no

N rated +ve yes/ -ve no N rated -ve yes/ +ve no

The term ‘positive’ means ‘yes’ ratings for positive adjectives and ‘no’ ratings for negative adjectives whereas ‘negative’ means ‘yes’ ratings for negative words and ‘no’ ratings for positive words.

Table 3.23. Mean proportion of phrases recalled (s.d.) on self-referent encoding task.

SELF OTHER

GROUP

Positive Negative Positive Negative

C urrent users

0.50 (0.32) 0.51 (0.54) 0.35 (0.22) 0.41 (0.40)

Ex-users 0.36 (0.20) 0.43 (0.33) 0.41 (0.27) 0.27 (0.26) Controls 0.50 (0.23) 0.35 (0.27) 0.28 (0.21) 0.51 (0.46)

The between-subjects measure was GROUP and the within-subjects measures were SELF/OTHER (whether the adjective referred to oneself or the ‘other’ person) and POSITIVE/NEGATIVE (whether the adjective was ‘positive’ or ‘negative’ in meaning). There was a 3-way interaction Group*Self/Other*Positive/Negative [F (2,48)= 4.08, p<0.05]. As can be seen in Figure 3.8, ex-users recalled a similar proportion o f self and other-positive adjectives whereas current users and controls recalled more self-positive than other-positive adjectives. Current users and controls recalled a greater proportion o f other-negative than other-positive adjectives. However, ex-users recalled more positive than negative adjectives about other people. Current users recalled a similar proportion o f self-positive and self-negative adjectives, as did ex-users. However, controls recalled more self-positive than self-negative words. Current users also recalled more self than other-negative words, as did ex-users. Controls recalled more other-negative than self­ negative words.

In summary, ex-users recalled more se If-negative than self-positive adjectives and were less likely to recall negative adjectives about others than current users or controls. However, controls recalled more positive adjectives than negative about themselves and were more likely to recall negative adjective about others. Current users performed in

between ex-users and controls, recalling an equal number o f self-positive and negative words, but also being less positive about other people than ex-users.

Figure 3.8. G roup*sel£^other*positive/negative interaction on self-referent encoding task.

0.6

Proportion of 0.4