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differed in data collection environment (Study I: sleep laboratory; Study II: home setting), dream sampling procedure (Study I: REM awakenings throughout the night; Study II: morning awakenings) and included different groups of participants and

With SR, as compared with ER, a significantly larger number of dreams were rated as affective (ES for Study I: r = .62, p < .001; ES for Study II: r = .61, p < .001) and positive (ES for Study I: r = .62, p < .001; ES for Study II: r = .59, p < .001) (see Figure 7). Whereas with SR (almost) all of the dreams were rated as affective (100 % in Study I; 97.5 % in Study II), with ER only approximately one-third (28.7 % in Study I) or half (47.8 % in Study II) of the reports were rated as affective (see Table 9). While with SR more than half of the dreams were rated as positive (79.1 % in Study I; 55.8 % in Study II), with ER only about ten percent (9.6 % in Study I; 12.5 % in Study II) of the reports were rated as positive. The number of negative dreams was similar with the two rating methods. In Study I, there were no significant differences between SR and ER (ES r = .05, p > .05), with both ratings yielding approximately ten percent negative dreams (12.1% with SR, 11.3% with ER). Although in Study II significantly more dreams were rated as negative with SR, as compared with ER, the difference was small (ES r = .25, p = .017), with both methods resulting in about one-third of negative dreams (35.3 % with SR; 28.1 % with ER). In addition, with SR dreams were rated to contain more PA and NA than with ER (ES for Study I: rPA = .62, rNA = .62, ps < .001; ES for Study II: rPA = .62, rNA = .62, ps < .001), although the difference was larger for PA than for NA (ES for Study I: r = .62, p < .001; ES for Study II: d = 0.68, p < .001).

Figure 7. Mean number of affective dreams and affective states per dream, as evaluated with

self-ratings (SR) and external ratings (ER). PA = positive affect. NA = negative affect. Study I: PA (min = 0; max = 9), NA (min = 0; max = 9). Study II: PA (min = 0, max = 10), NA (min = 0, max = 10). Error bars represent standard deviation. *p < .05. ***p < .001.

Thus, the two methods differed mostly in the estimation of positive dreams and PA per dream. This was supported by results showing that the NA subscales of SR and ER were positively correlated (Study I: rs = .52, p = .032; Study II: rs = .49, p = .001), whereas no significant relationships were observed between the PA subscales (Study I: rs = .18, p = .498; Study II: rs = .22, p = .152) (see Table 10). Table 10. Intercorrelations between positive affect (PA) and negative affect (NA) subscales

of self-ratings (SR) and external ratings (ER)

ER PA ER NA SR PA SR NA ER PA 1.00ab ER NA .49*a .49***b 1.00ab SR PA .18a .22b –.02a .02b 1.00ab SR NA .24a .23b .52*a .49***b .28a .25b 1.00ab

Note. a_{Study I (Sikka, Valli, Virta, & Revonsuo, 2014).} b_{Study II (Sikka, Feilhauer, Valli, &}

Revonsuo, 2017). *p < .05. ***p < .001.

Regarding discrete affective states, almost all of the different affect items were rated to occur more frequently with SR than with ER (Study I: 12 out of 20, ES r = .47 – .61, ps < .05; Study II: 20 out of 20, ES r = .45 – .60, ps < .001). Thus, the differences between SR and ER were not due to specific affective states. The same items were among the most frequently rated with both methods across the two studies: ‘Interested/Alert/Curious’, ‘Joyful/Glad/Happy’, and ‘Amused/Fun- loving/Giggly’ among the PA items, and ‘Angry/Irritated/Annoyed’ and ‘Stressed/Nervous/Overwhelmed’ among the NA items. In Study II, ‘Scared/Fearful/Afraid’ was also frequently rated among the NA items (with both SR and ER), but it was less frequent in Study I.

Considered separately, the two measurement methods provided a very different picture regarding the affective nature of dreams. With SR, there were significantly more positive than negative dreams (ES for Study I: r = .62, p < .001; ES for Study II: r = .31, p = .003) and more PA than NA per dream (ES for Study I: r = .62, p < .001; ES for Study II: d = 0.55, p = .001). With ER, however, the number of positive and negative dreams (ES r = .09, p > .05), as well as of PA and NA per dream (ES r = .15, p > .05), were either not significantly different (Study I), or

negative dreams (ES r = .38, p < .001) and NA per dream (ES r = .39, p < .001) prevailed (Study II). Thus, whereas with SR dreams appeared to be mostly positive, with ER they appeared to be either rather balanced (Study I) or mostly negative (Study II).

Study II showed that whether ER of dream reports appeared to be mostly negative or to have a more balanced affective tone depended on whether the reports were provided by women or men. Women expressed more NA in their dream reports than men (ES r = .33, p = .030) and, as a result, had also more negative dream reports in general (ES r = .33, p = .029)18 _{(see Figure 8). When analysing results for men} and women separately, an interesting pattern of results emerged. Women had more negative than positive dream reports (ES r = .47, p < .001) and more NA than PA per report (ES r = .47, p < .001), whereas the number of positive and negative dream reports (ES r = .23, p = .203) and PA and NA per dream report (ES r = .18, p = .336) was balanced for men. This difference could not be explained by report length, because the reports of men and women did not differ in that regard (ES r = .06). Further analyses demonstrated that the NA scales of SR and ER were strongly positively correlated for women (rs = .70, p < .001) but not for men (rs = .12, p = .653). This suggests that how women rated negative dream affect corresponded better to how they expressed it in their dream reports and indicates that men may have underreported NA in their dream reports. No significant gender differences were observed in Study I, although women tended to express more NA in their dream reports in that study as well19_.

18 _{The total number of dream reports provided by women (M = 12.61, SD = 5.92,}

Mdn = 11.00) and men (M = 12.44, SD = 5.54, Mdn = 11.50) did not differ (Mann Whitney U = 221.00, Z = –0.073, p = .947, r = .011).

19 _{Although women (M = 0.25, SD = 0.24, Mdn = 0.20) expressed more NA in their dream}

reports than men (M = 0.06, SD = 0.12, Mdn = 0.00), the difference was not statistically significant (Mann Whitney U = 17.500, Z = –1.804, p = .088, r = .44).

Figure 8. Average number of dream reports and affect expressed in dream reports separately

for women (N = 28) and men (N = 16). Error bars represent standard deviation. *p < .05. ***p < .001.

As shown above (see Table 9), dreams in Study II appeared relatively more affective and negative than in Study I, particularly with regard to ER. Whereas in Study I only about one-third (28.7 %) of the dream reports were rated to contain affective states, in Study II almost half (47.8 %) of the reports were rated as affective. While in Study I only about ten percent (11.3 %) of reports were negatively valenced, in Study II more than twice as many were (28.1 %). This raises the question of what may underlie the differences between the two studies. One possible explanation is differences in reporting modality: whereas in Study I dream reports were provided orally, in Study II they were written down. However, the fact that SR also yielded a larger percentage of negative dreams (12.2 % in Study I; 35.3 % in Study II) makes this explanation is unlikely. This brings us to the second possible explanation—differences in the data collection environment. Whereas in Study I data were collected in the sleep laboratory, in Study II data were collected in participants’ home environments. Are home dreams more affective and more negatively valenced than laboratory dreams? The results of Study III help shed light on this question.