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Effects of induced elation-depression on the accessibility of memories of happy and unhappy experiences
EFFECTS OF INDUCED ELATION-DEPRESSION ON THE ACCESSIBILITY OF MEMORIES OF HAPPY AND UNHAPPY EXPERIENCES JOHN D. TEASDALE*, ROBERT TAYLOR and SARAH J. FOGARTY Department of Psychiatry, University of Oxford, England (Received
11 December 1979)
Summary-Elated and depressed moods were induced in student volunteers on separate occasions. On each occasion they retrieved past real-life experiences associated to stimulus words presented. Subjects subsequently rated the experiences for happiness-unhappiness and pleasantness-unpleasantness on a third occasion in a neutral mood state. Extremely unhappy memories were significantly more likely to be retrieved in the depressed mood than in the elated mood. Extremely happy memories were significantly more likely to be retrieved in the elated mood than in the depressed mood. Measures of latency of retrieval showed a significant interaction between mood state and type of memory. The results confirm the generality of previous findings in suggesting an effect of mood state on the accessibility of dilTerent types of cognition. The results are considered in relation to mood as a context in contextual-specific encoding and retrieval. and in relation to models and treatment of clinical conditions.
The effect of affective state 011 rne accessibility of different types of memory has been relatively little investigated. Teasdale and Fogarty (1979) studied the effects of induced happy and depressed moods on the retrieval of memories of past pleasant and unpleasant experiences in student subjects. Using the latency to retrieve a memory as a measure of its accessibility they found that pleasant memories were less accessible in the depressed state than in the happy state, although there was no difference between conditions in the accessibility of unpleasant memories. These results partially replicated the findings of a correlational study in depressed patients previously reported by Lloyd and Lishman (1975). They had found that increasing severity of depression was (non-significantly) associated with increased latency for retrieval of pleasant experiences and significantly associated with decreased latency for retrieval of unpleasant experiences. Isen et al. (1978), using a different experimental paradigm, found that experience of success was followed by greater subsequent recall of previously learned positive trait words than was the experience of failure. No effect of success or failure on recall of neutral or negative words was obtained. They interpreted their results as demonstrating the effect of good mood, induced by success, selectively increasing the accessibility of positive cognitions. In their case, probability of recall, rather than latency, was used as a measure of accessibility. The procedures used by Teasdale and Fogarty (1979) and Lloyd and Lishman (1975), on the one hand, and Isen et al. (1978) on the other, are in many ways complementary. The measure of -accessibility used by Isen et al. (1978), probability of recall, has more obvious relevance to everyday life and clinical phenomenology than the latency measure used by Teasdale and Fogarty (1979) and Lloyd and Lishman (1975). On the other hand, the types of memories studied by these latter workers, past real-life experiences, seem more relevant to everyday behaviour than the memory for word lists studied by Isen et al. (1978). If probability of recall and latency of retrieval both indicate memory accessibility in a similar way, it should be possible to modify the Teasdale and Fogarty (1979) procedure to study the effects of experimentally manipulated mood on the probability of recall of different types of past real-life experiences. This would (1) provide an opportunity to examine the generality of previous findings and (2) allow further investigation of *Requests for reprints should be sent to John D. Teasdale. Department The Warneford Hospital. Oxford OX3 7JX. England.
of Psychiatry, University of Oxford,
340
JOHN D. TEASDALE, ROBERTTAYLORand SARAHJ. FCXARTY
the finding, obtained by both Isen et al. (1978) and Teasdale and Fogarty (1979), that the effect of mood manipulations appeared largely restricted to the accessibility of positive cognitions, negative cognitions being relatively unaffected. Thus, the purpose of the present experiment was to examine the effects of experimentally induced depressed and elated moods on the probability of recall of memories of past happy and unhappy experiences. METHOD
Overview
Each subject was seen on three occasions. On the first two occasions subjects received a depressed mood induction on one occasion and an elated mood induction on the other. Following mood induction subjects were presented with a series of words and asked to recall a past real-life experience associated with each word and briefly to describe the experience. On the third occasion these experiences were rated for their happiness and pleasantness. Latency of retrieval of the memories in the first two sessions was also measured. Subjects
Forty-three female student subjects were recruited from Oxford Polytechnic and Dorset House School of Occupational Therapy, Oxford. The mean age of the 20 subjects meeting the acceptance criteria for the study (see below) was 19.2 yr. Experimenral design
A Latin Square with repeated measures design (Winer, 1962, p. 542) was used and is shown in Table 1. Each subject received both elation and depression mood inductions, counterbalanced for order across subjects. List A and List B in Table 1 refer to two different word lists (see below). Each subject received both word lists, counterbalanced for order and mood induction across subjects. Subjects were randomly allocated to the groups shown in Table 1 until there were five subjects meeting the acceptance criteria in each group. Apparatus Mood measures. Subjects rated their mood using dards bearing O-100 line scales, 10 cm long, on which 0 was labelled “I do not feel at all X” and 100 was labelled “I feel extremely X”. For different cards X was “anxious”, “despondent” and “happy”. “AT THIS MOMENT” was typed at the top of each card to indicate that it was instantaneous mood that was to be rated. Mood induction. This was similar to the procedure described by Velten (1968). For each mood induction condition subjects read 30 cards bearing typed self-referent statements. For the depressed mood induction, initial statements were mildly depressing in content, for example, “Things aren’t quite like I would like them to be”, proceeding through more depressing statements, for example, “Looking back on my life I wonder if I have accomplished anything really worthwhile”, to statements such as “I feel downhearted and miserable”. For the elation mood induction, initial statements were mildly euphoric in content, for example, “All in all, I’m pretty pleased with the way things are going”
Table 1. Experimental design Group Ia Ib Ha IIb
Depressed induction
Happy induction Occasion Occasion Occasion Occasion
l-List 2-List l-List 2-List
A A B B
Occasion Occasion Occasion Occasion
2-List l-List 2-List l-List
B B A A
Elation-depression
and accessibility of memories
341
proceeding through more euphoric statements, for example, “Life is so full and interesting it’s great to be alive!” to statements such as “I feel so good I almost feel like laughing”. Word lists. List A consisted of the words: rrain, ice, wood, lerrer, house, race, shoe, window, sign, meeting, travel, reading, road, machine, rain, room, water, tunnel, dream and secret. List B consisted of the words: speech, cooking, step, sound, people, mist, srarion, children, church, chair, stone, paper, smell, hear, darkness, street, trip, swimming, class and public. An electronic timer was activated automatically when the stimulus word was presented, and terminated by subjects pressing a button on the arm of their chair as soon as they had recalled an experience from memory. Retrieval latency was then read from the timer, which automatically reset. Procedure
On arrival, subjects completed the Beck Depression Inventory (Beck, 1967) and the Eysenck Personality Inventory Form B (Eysenck and Eysenck, 1964). The experiment was conducted in a windowless, sound-attenuated room in which the subject sat in a comfortable chair. The experimenter sat behind, out of sight. Subjects were told that the experiment was about the recall of real-life personal experiences. They were informed that they would hear a series of stimulus words and would be asked to recall to each word an experience associated in some way with that word. They were told that all experiences were acceptable so long as they were brought to mind by the stimulus word and were definite experiences from memory, not merely current thought associations. Experiences had to be specific; it did not matter how long ago they had occurred. Subjects were told that as soon as they had recalled an experience they should press the button and say out loud a few words to enable them to recall the incident more fully later on. They were told that if they did not wish, for personal reasons, to elaborate on particular memories that was acceptable. They were given an example of recalling an experience to a stimulus word. Subjects were toldnot to worry if they found it difficult to find a memory as it was easier to associate to some words than to others. The overall procedure was then outlined, emphasising the importance of trying to become fully involved in the mood induction procedure. All further instructions were delivered by tape-recorder. These told the subjects to read to themselves the statements typed on the mood induction cards which they had been given, and to try to feel the mood suggested. They were asked to try to get themselves into the state where their feelings would be like those suggested by the statements. They were told they would have 15 s on each card, and a tone signal would indicate when to turn over the next card. After 31 tone signals at 15 s intervals subjects were looking at a blank card, having read the 30 mood induction statements. They were reminded to press the button on recalling a memory and to describe it in a few words. They were then asked to retrieve a memory to the first stimulus word. Latency of retrieval was recorded, a latency of 15 s being recorded if no memory had been recalled in 15 s. The experimenter noted the brief description of the experience. In order to maintain the induced mood subjects read two mood induction cards after each memory retrieval. This procedure continued until all 20 words in the list had been presented. Subjects rated their mood on the three scales and counted from 1 to 10 “in their own time”, this being tape-recorded, at the following points in the experiment : (1) immediately before reading the first mood induction card; (2) immediately after reading the 30 mood induction statements; (3) after briefly describing the memory associated with the tenth stimulus word; and (4) after briefly describing the memory associated with the last stimulus word. The tape-recordings of subjects counting from 1 to 10 were subsequently played back through a Devices Ml9 Polygraph to produce a visual “speech print” from which the total duration of counting was measured. This provided a measure of rate of automatic speech which has been shown to be sensitive to changes in depression (Szabadi, Bradshaw and Besson, 1976; Teasdale, Fogarty and Williams, 1980). At the end of the experimental session subjects were asked to write on separate sheets of paper more detailed accounts of the experiences they had recalled, using their brief BR.TIX4 ”
342
JOHN D. TEASDALE,ROBERTTAYLOR and SARAH 1. F~CARTY
descriptions recorded by the experimenter as cues. They were asked to write just enough to remind themselves accurately of the incident if they were given the sheet back in a week’s time. The second experimental session took place on average 5 days later. The procedure was the same as in the first session, except that subjects who had previously received the elation mood induction received the depressed mood induction and subjects who had previously received the depressed mood induction received the elation mood induction. The third experimental session took place on average 3 days after the second session. Subjects were presented in random order with the accounts they had written of the experiences recalled in the first two sessions. They were asked to rate the original experiences for how pleasant or unpleasant the experience had been and how happy or unhappy they had felt at the time of the original experience. In each case scales ranging from - 3 (extremely unpleasant/unhappy) through -2 (moderately unpleasant/unhappy), - 1 (slightly unpleasant/unhappy), 0 (neither pleasant nor unpleasant/happy nor unhappy), + 1 (sli~tly plea~nt~appy~ +2 (moderately pleasant,~appy), to +3 (extremely pleasant/happy) were used. After completing this for all experiences retrieved, subjects were debriefed, thanked and paid. Because the interest of the study was in the effects of differences in depressed mood. before the experiment began a criterion was chosen to define an adequate difference in mood between the two mood conditions. This was that the despondency rating immediately after the 30 depressed mood induction cards should be at least 20 points greater than the despondency rating immediately after the 30 elation mood induction cards. Subjects failing to meet this criterion were excluded from the main analysis, and testing continued until there were five subjects meeting the criterion in each of the groups shown in Table 1. RESULTS Extremely unhappy memories were more probable in the depresSed condition than in the elated condition. Extremely happy memories were more probable in the elated condition than in the depressed condition. Latency of retrieval showed a significant interaction between mood state and type of memory. Eflects of mood induction
Table 2 shows the effects of the elation and depressed mood inductions on the mood and counting-time measures. These results are based on the means from the three occasions of measurement following each mood induction. The results of dependent r-tests comparing these measures in the two conditions are also shown. The difference in d~pondency following the two mood inductions was, of course, guaranteed by the criterion used to select subjects. Following depressed mood induction subjects were also significantly more anxious, less happy and took longer to count from 1 to 10. ~i~re~tiuf
e@cts on pro~u~j~iry
of retriever
of~uppy
and unhappy
experiences
Table 2 shows the’ percentage of the memories retrieved which were rated as happy (-1-1, +2 or +3)or unhappy (-1, -2 or -3) in the two mood conditions. Because of the non-normality of the distributions sign-tests were used to compare the percentages in the two conditions. Happy memories were signifi~ntly more probable in the elation condition than in the depressed condition (Table 2), only 2 out of the 20 subjects showing the reverse pattern. Unhappy memories were more probable in the depressed condition but not significantly so. Table 2 also shows the percentage of the memories retrieved which were rated as pleasant (+ I, +2 or +3) or unpleasant (- 1, -2 or -3) in the two mood conditions. Both differences in percentages were in the same direction as for happy and unhappy memories, but neither was significant. Ratings of pleasantness and happiness of experiences were not always highIy related; the correlation between the two ratings for all memories was 0.70. WhiIe 91% of memories rated pleasant were also rated happy. 29% of
Elation-depression
and accessibility of memories
343
Table 2. Effects of elation and depression mood inductions Elation induction
Depression induction
M
M
Measure Despondency* Anxiety* Happiness* Counting time (s)t O0Happy memories ” (, Unhappy memories no Pleasant memories a” Unpleasant memories Latency happy memories (s)S Latency unhappy memories (s):
Statistic
p (2 tail)
r = 10.66 t = 2.20 r = 9.14 r = 2.29 sign test sign test sign test sign test
8.5 18.5 71.7 5.75 68.8 19.9 56.1 33.9
44.8 28.5 37.0 6.32 51.4 28.3 44.5 46.1
4.89
5.88
Tukey
0.06
6.09
5.39
Tukey
N.S.
N.B. n = 20 for each mean. * Mood measured on O-100 scales. t Time taken to count from 1 to 10. $ Latencies subjected to log transformation to normalise. Means for latencies calculated by antilogarithm from transformed data
memories rated unpleasant were rated happy also. This occurred because a number of subjects recalled experiences during which they had felt happy, although the experiences themselves they rated ‘objectively’ as unpleasant. An example of such an experience would be a camping weekend in which it had rained continuously, and the subject had been soaked through, but she had, nonetheless, enjoyed herself. Of 79 such experiences recalled, 47 were recalled in the elated condition and .32 in the depressed condition. As a significant effect of mood was only obtained on the happy-unhappy categorisation, further analysis was restricted to this dimension. Table 3 shows the percentage of memories at different happiness ratings in depressed and elated moods. The ratios of these percentages are shown graphically in Fig. 1. Extremely unhappy experiences were retrieved significantly more often in the depressed condition than in the elated condition, and extremely happy experiences were retrieved significantly more often in the elated condition than in the depressed condition. The marginally sign&ant difference in percentage of memories rated 0 probably simply reflects the fact that the excess of happy memories in the elated condition is not totally compensated by the excess of unhappy memories in the depressed condition. Some indication of the extent of the differential effect of mood on retrieval of happy and unhappy memories is the fact that while extremely happy memories are approximately eight times more probable than extremely unhappy memories in the elated condition, they are only approximately twice as probable in the depressed condition. Differential effects of mood on latency of retrieval oJ happy and unhappy memories
Mean latency of retrieval was calculated separately for happy memories and unhappy memories for each subject in each mood condition. The results are summarised in Table 2.
Table 3. Percentage of memories at different happiness ratings in depressed and elated moods Happiness rating no in elated mood (E) ’ in depressed mood (D) iatio E/D Significance of difference m “g E-D (sign test, 2-tail)
-3 3.6 8.9 0.40
-2 4.1 7.0 0.59
-1 12.2 12.3 0.99
p < 0.008
N.S.
N.S.
0 11.3 20.3 0.56
p
t-1 15.5 13.1 1.18
2+6.25 20.5 1.29
N.S.
N.S.
+3 26.8 17.8 1.51
p
JOHN D.
344
TEASDALE,
ROBERTTAYLOR
Happiness
Fig. 1. Ratio
and SARAH J.F~GARTV
rating
E/D for memories at different happiness ratings; E/D = O,, of memories mood at a given rating/% of memories in depressed mood at that rating.
in
elated
A 2 x 2 analysis of variance (elated-depressed mood x happy-unhappy memories) yielded no significant main effect for mood or type of memory, but a highly significant interaction between these two factors [F (1,19) = 10.09, p = 0.005]. The interaction, which is shown in Fig. 2, was examined by Tukey test. This showed that, within the elated condition. happy memories were recalled significantly faster (p < 0.05) than unhappy memories, and there was a tendency (p < 0.06) for happy memories to be recalled faster in the elated condition than in the depressed condition. Overall, unhappy memories were recalled non-significantly faster than happy memories within the depressed condition, and non-significantly faster in the depressed condition than in the elated condition. However, extremely unhappy memories (those rated - 3) were actually recalled nonsignificantly faster in the elated condition than in the depressed condition.
6.5 6.0
z 5.5 v ,' c 5.0 z '; ; 4.5 z I
4.0
-I ‘r
ol Elated
Depressed Mood
Fig.
2. Interaction
(p = 0.005) between mood induction (elation vs depression) memory (happy vs. unhappy) for latency of memory retrieval.
and
type
of
Elation-depression
and accessibility
of memories
345
Correlational analysis If the mood inductions have different effects on the probability of retrieval of happy and unhappy memories because of the differences in mood they produce, we would expect some relationship between the extent of the ditference in mood between the two conditions and the extent of differences in probability of retrieval. To examine this correlations were calculated for all the subjects tested between the differences in percentage of happy memories in the two conditions and the differences in mood. Significant correlations were obtained for the differences in mean despondency [r (41) = 0.46, p < 0.011, the differences in mean happiness [r (41) = -0.32, p < 0.051 and the differences in an overall measure of ‘bad mood’, calculated by adding the mean scores for despondency and anxiety and subtracting the mean score for happiness [r(41) = 0.37, p < 0.05]. The correlation for differences in mean anxiety [r (41) = 0.033 was not significant.
DISCUSSION The present finding that induced mood differentially affected the probability of retrieving memories of happy or unhappy past experiences confirms the generality of previous findings. Teasdale and Fogarty (1979) found differential effects of mood induction on the latency to recall such experiences, and Isen et al. (1978) found effects on the extent of recall of positive trait words previously learned in the experimental setting. Together, these results lend support to the notion that induced mood states modify the accessibility of different types of cognition. Teasdale and Fogarty (1979) and Isen et al. (1978) found the effects of mood restricted to the accessibility of positive cognitions, with little effect on negative cognitions. By contrast, the present study found effects on both positive and negative cognitions; extremely happy memories were more common in the elated than in the depressed mood, and extremely unhappy memories were more common in the depressed mood than in the elated mood. The first of these effects does not necessarily account for the second. although, of course, there would necessarily be some interdependence between the percentage of memories at different happiness ratings as they all had to add up to 1009;. The effects of mood on latency measures in this study were, as in our previous study (Teasdale and Fogarty, 1979) more apparent for positive memories. Indeed, although extremely unhappy memories were retrieved significantly more often in the depressed mood than in the elated mood, their latency of retrieval was nonsignificantly faster in the elated condition. Thus, in the present paradigm, latency and probability of retrieval do not appear to be equivalent measures of accessibility for extremely negative cognitions. Further, while effects of mood on the probability of recalling negative cognitions could be demonstrated in the present paradigm, the same was not true in the paradigm studied by Isen et al. (1978). The reasons for this are not clear. In the present study a significant effect on probability for negative cognitions was only obtained for memories of past real-life experiences rated as extremely unhappy. By contrast, the negative cognitions studied by Isen et al. (1978) were ,negative personality trait words forming parts of word lists learned in the experimental session. As in our previous study (Teasdale and Fogarty, 1979) the observed differences in accessibility of cognitions following the two mood inductions could have resulted either from differences in the mood induced or directly from differences in the mood induction procedures. In both studies, correlational evidence showed significant covariation across subjects between the extent to which mood actually differed in the two conditions and the extent of differences in accessibility of cognitions. As all subjects received the same induction procedures this evidence supports the idea that the differences in accessibility actually resulted from differences in mood. However, such correlational evidence cannot reject the alternative explanation. For example, subjects might vary in the extent ‘to which the mood induction self-statements generated thoughts of specific happy or unhappy past experiences. to the class of memories pattern of correlations.
Such thoughts might both affect mood and prime accessibility of similar past experiences. This could lead to the observed
346
JOHN D. TEASDALE. ROBERT TAYLOR and SARAH J. FIXARTY
If mood as such does, in fact, differentially modify the accessibility of different types of cognition, how does this occur? In discussing our previous results (Teasdale and Fogarty. 1979) we considered the possibility that this was an example of context-specific encoding and retrieval in which mood state acted as a context. This would suggest that memories of positive experiences would be more likely to be recalled in the elated mood because mood state at retrieval was similar to the happy mood state prevailing when the memory was encoded. For similar reasons, memories of negative experiences would be more likely to be recalled in the depressed mood state as this would approximate more closely the initial context in which they were encoded. The somewhat different results obtained for ratings of pleasantness-unpleasantness and happiness-unhappiness in the present study are interesting in this respect. Happiness ratings appeared to be the more important. When an experience was ‘objectively’ rated as unpleasant but the prevailing subjective state at encoding was happy the initial mood state appeared to be the better predictor of subsequent retrieval in various mood states. This finding. if reliable, would support the mood-dependent context-specific encoding and retrieval explanation. Our present findings suggest quite a marked effect of induced mood state on the probability of recalling happy as compared to unhappy cognitions. If we can assume that clinical mood states have similar effects on the probability of naturally occurring thoughts there are important implications for our understanding and treatment of these disorders. We have already discussed these elsewhere (Teasdale and Fogarty, 1979). The most important implication is that there may be a reciprocal relationship between cognition and emotion. Cognitive models of depression and other emotional disorders (e.g. Beck, 1976) propose that cognitions with particular content lead to emotional states. Our findings suggest that these states may then selectively increase the likelihood of cognitions of the type likely to perpetuate them and selectively decrease the likelihood of cognitions of the type likely to modify them. It is possible that in certain circumstances such a reciprocal relationship might lead to self-maintaining emotional states. Where this occurs therapy might then usefully aim to correct such a biasing effect of mood state on cognitive accessibility (e.g. Beck. 1976). Acknowledgements-This research was supported by the Medical Research The authors are very grateful to Donald E. Broadbent for helpful comments
Council of the United Kingdom. on an earlier draft of this article.
REFERENCES BECK A. T. (1967) Depression: Clinical. Experimental and Theoretical Aspeers. Harper and Row. New York. BECK A. T. (1976) Cognitive Therapy and rhe Emotional Disorders. International Universities Press. New York. EYSENCK H. J. and EYSENCK S. B. G. (1964) Manual of the Eysenck Personaliry Inrenrorv. University of London Press, London. ISEN A. M., SHALKER T. E., CLARK M. and KARP L. (1978) Affect. accessibility of material in memory. and behavior: a cognitive loop? J. Personalirg sot. Psycho/. 36. l-12. LLOYD G. G. and LISHMAN W. A. (1975) ERect of depression on the speed of recall of pleasant and unpleasant experiences. Psycho/. Med. 5, 173-180. SZABADI E., BRADSHAW C. M. and BES~N J. A. 0. (1976) Elongation of pause-time in speech: a simple. objective measure of motor retardation in depression. Br. J. Psychiar. 129. 592-597. TEASDALE J. D. and FCIGARTY S. J. (1979) Differential effects of induced mood on retrieval of pleasant and unpleasant memories from episodic memory. J. abnorm. Psychof. 88, 248-257. TEASDALE J. D., F~GARTY S. J. and WILLIAMS J. M. G. Speech rate as a measure of short-term variation m depression. In press. &if. J. Sot. Clin. Psychol. VELTEN E. (1968) A laboratory task for inductionof mood states. Behar. Res. Ther. 6. 473482. WINER B. J. (1962) Srarisricol Principles in Experimental Design. McGraw-Hill. New York.
11 December 1979)
Summary-Elated and depressed moods were induced in student volunteers on separate occasions. On each occasion they retrieved past real-life experiences associated to stimulus words presented. Subjects subsequently rated the experiences for happiness-unhappiness and pleasantness-unpleasantness on a third occasion in a neutral mood state. Extremely unhappy memories were significantly more likely to be retrieved in the depressed mood than in the elated mood. Extremely happy memories were significantly more likely to be retrieved in the elated mood than in the depressed mood. Measures of latency of retrieval showed a significant interaction between mood state and type of memory. The results confirm the generality of previous findings in suggesting an effect of mood state on the accessibility of dilTerent types of cognition. The results are considered in relation to mood as a context in contextual-specific encoding and retrieval. and in relation to models and treatment of clinical conditions.
The effect of affective state 011 rne accessibility of different types of memory has been relatively little investigated. Teasdale and Fogarty (1979) studied the effects of induced happy and depressed moods on the retrieval of memories of past pleasant and unpleasant experiences in student subjects. Using the latency to retrieve a memory as a measure of its accessibility they found that pleasant memories were less accessible in the depressed state than in the happy state, although there was no difference between conditions in the accessibility of unpleasant memories. These results partially replicated the findings of a correlational study in depressed patients previously reported by Lloyd and Lishman (1975). They had found that increasing severity of depression was (non-significantly) associated with increased latency for retrieval of pleasant experiences and significantly associated with decreased latency for retrieval of unpleasant experiences. Isen et al. (1978), using a different experimental paradigm, found that experience of success was followed by greater subsequent recall of previously learned positive trait words than was the experience of failure. No effect of success or failure on recall of neutral or negative words was obtained. They interpreted their results as demonstrating the effect of good mood, induced by success, selectively increasing the accessibility of positive cognitions. In their case, probability of recall, rather than latency, was used as a measure of accessibility. The procedures used by Teasdale and Fogarty (1979) and Lloyd and Lishman (1975), on the one hand, and Isen et al. (1978) on the other, are in many ways complementary. The measure of -accessibility used by Isen et al. (1978), probability of recall, has more obvious relevance to everyday life and clinical phenomenology than the latency measure used by Teasdale and Fogarty (1979) and Lloyd and Lishman (1975). On the other hand, the types of memories studied by these latter workers, past real-life experiences, seem more relevant to everyday behaviour than the memory for word lists studied by Isen et al. (1978). If probability of recall and latency of retrieval both indicate memory accessibility in a similar way, it should be possible to modify the Teasdale and Fogarty (1979) procedure to study the effects of experimentally manipulated mood on the probability of recall of different types of past real-life experiences. This would (1) provide an opportunity to examine the generality of previous findings and (2) allow further investigation of *Requests for reprints should be sent to John D. Teasdale. Department The Warneford Hospital. Oxford OX3 7JX. England.
of Psychiatry, University of Oxford,
340
JOHN D. TEASDALE, ROBERTTAYLORand SARAHJ. FCXARTY
the finding, obtained by both Isen et al. (1978) and Teasdale and Fogarty (1979), that the effect of mood manipulations appeared largely restricted to the accessibility of positive cognitions, negative cognitions being relatively unaffected. Thus, the purpose of the present experiment was to examine the effects of experimentally induced depressed and elated moods on the probability of recall of memories of past happy and unhappy experiences. METHOD
Overview
Each subject was seen on three occasions. On the first two occasions subjects received a depressed mood induction on one occasion and an elated mood induction on the other. Following mood induction subjects were presented with a series of words and asked to recall a past real-life experience associated with each word and briefly to describe the experience. On the third occasion these experiences were rated for their happiness and pleasantness. Latency of retrieval of the memories in the first two sessions was also measured. Subjects
Forty-three female student subjects were recruited from Oxford Polytechnic and Dorset House School of Occupational Therapy, Oxford. The mean age of the 20 subjects meeting the acceptance criteria for the study (see below) was 19.2 yr. Experimenral design
A Latin Square with repeated measures design (Winer, 1962, p. 542) was used and is shown in Table 1. Each subject received both elation and depression mood inductions, counterbalanced for order across subjects. List A and List B in Table 1 refer to two different word lists (see below). Each subject received both word lists, counterbalanced for order and mood induction across subjects. Subjects were randomly allocated to the groups shown in Table 1 until there were five subjects meeting the acceptance criteria in each group. Apparatus Mood measures. Subjects rated their mood using dards bearing O-100 line scales, 10 cm long, on which 0 was labelled “I do not feel at all X” and 100 was labelled “I feel extremely X”. For different cards X was “anxious”, “despondent” and “happy”. “AT THIS MOMENT” was typed at the top of each card to indicate that it was instantaneous mood that was to be rated. Mood induction. This was similar to the procedure described by Velten (1968). For each mood induction condition subjects read 30 cards bearing typed self-referent statements. For the depressed mood induction, initial statements were mildly depressing in content, for example, “Things aren’t quite like I would like them to be”, proceeding through more depressing statements, for example, “Looking back on my life I wonder if I have accomplished anything really worthwhile”, to statements such as “I feel downhearted and miserable”. For the elation mood induction, initial statements were mildly euphoric in content, for example, “All in all, I’m pretty pleased with the way things are going”
Table 1. Experimental design Group Ia Ib Ha IIb
Depressed induction
Happy induction Occasion Occasion Occasion Occasion
l-List 2-List l-List 2-List
A A B B
Occasion Occasion Occasion Occasion
2-List l-List 2-List l-List
B B A A
Elation-depression
and accessibility of memories
341
proceeding through more euphoric statements, for example, “Life is so full and interesting it’s great to be alive!” to statements such as “I feel so good I almost feel like laughing”. Word lists. List A consisted of the words: rrain, ice, wood, lerrer, house, race, shoe, window, sign, meeting, travel, reading, road, machine, rain, room, water, tunnel, dream and secret. List B consisted of the words: speech, cooking, step, sound, people, mist, srarion, children, church, chair, stone, paper, smell, hear, darkness, street, trip, swimming, class and public. An electronic timer was activated automatically when the stimulus word was presented, and terminated by subjects pressing a button on the arm of their chair as soon as they had recalled an experience from memory. Retrieval latency was then read from the timer, which automatically reset. Procedure
On arrival, subjects completed the Beck Depression Inventory (Beck, 1967) and the Eysenck Personality Inventory Form B (Eysenck and Eysenck, 1964). The experiment was conducted in a windowless, sound-attenuated room in which the subject sat in a comfortable chair. The experimenter sat behind, out of sight. Subjects were told that the experiment was about the recall of real-life personal experiences. They were informed that they would hear a series of stimulus words and would be asked to recall to each word an experience associated in some way with that word. They were told that all experiences were acceptable so long as they were brought to mind by the stimulus word and were definite experiences from memory, not merely current thought associations. Experiences had to be specific; it did not matter how long ago they had occurred. Subjects were told that as soon as they had recalled an experience they should press the button and say out loud a few words to enable them to recall the incident more fully later on. They were told that if they did not wish, for personal reasons, to elaborate on particular memories that was acceptable. They were given an example of recalling an experience to a stimulus word. Subjects were toldnot to worry if they found it difficult to find a memory as it was easier to associate to some words than to others. The overall procedure was then outlined, emphasising the importance of trying to become fully involved in the mood induction procedure. All further instructions were delivered by tape-recorder. These told the subjects to read to themselves the statements typed on the mood induction cards which they had been given, and to try to feel the mood suggested. They were asked to try to get themselves into the state where their feelings would be like those suggested by the statements. They were told they would have 15 s on each card, and a tone signal would indicate when to turn over the next card. After 31 tone signals at 15 s intervals subjects were looking at a blank card, having read the 30 mood induction statements. They were reminded to press the button on recalling a memory and to describe it in a few words. They were then asked to retrieve a memory to the first stimulus word. Latency of retrieval was recorded, a latency of 15 s being recorded if no memory had been recalled in 15 s. The experimenter noted the brief description of the experience. In order to maintain the induced mood subjects read two mood induction cards after each memory retrieval. This procedure continued until all 20 words in the list had been presented. Subjects rated their mood on the three scales and counted from 1 to 10 “in their own time”, this being tape-recorded, at the following points in the experiment : (1) immediately before reading the first mood induction card; (2) immediately after reading the 30 mood induction statements; (3) after briefly describing the memory associated with the tenth stimulus word; and (4) after briefly describing the memory associated with the last stimulus word. The tape-recordings of subjects counting from 1 to 10 were subsequently played back through a Devices Ml9 Polygraph to produce a visual “speech print” from which the total duration of counting was measured. This provided a measure of rate of automatic speech which has been shown to be sensitive to changes in depression (Szabadi, Bradshaw and Besson, 1976; Teasdale, Fogarty and Williams, 1980). At the end of the experimental session subjects were asked to write on separate sheets of paper more detailed accounts of the experiences they had recalled, using their brief BR.TIX4 ”
342
JOHN D. TEASDALE,ROBERTTAYLOR and SARAH 1. F~CARTY
descriptions recorded by the experimenter as cues. They were asked to write just enough to remind themselves accurately of the incident if they were given the sheet back in a week’s time. The second experimental session took place on average 5 days later. The procedure was the same as in the first session, except that subjects who had previously received the elation mood induction received the depressed mood induction and subjects who had previously received the depressed mood induction received the elation mood induction. The third experimental session took place on average 3 days after the second session. Subjects were presented in random order with the accounts they had written of the experiences recalled in the first two sessions. They were asked to rate the original experiences for how pleasant or unpleasant the experience had been and how happy or unhappy they had felt at the time of the original experience. In each case scales ranging from - 3 (extremely unpleasant/unhappy) through -2 (moderately unpleasant/unhappy), - 1 (slightly unpleasant/unhappy), 0 (neither pleasant nor unpleasant/happy nor unhappy), + 1 (sli~tly plea~nt~appy~ +2 (moderately pleasant,~appy), to +3 (extremely pleasant/happy) were used. After completing this for all experiences retrieved, subjects were debriefed, thanked and paid. Because the interest of the study was in the effects of differences in depressed mood. before the experiment began a criterion was chosen to define an adequate difference in mood between the two mood conditions. This was that the despondency rating immediately after the 30 depressed mood induction cards should be at least 20 points greater than the despondency rating immediately after the 30 elation mood induction cards. Subjects failing to meet this criterion were excluded from the main analysis, and testing continued until there were five subjects meeting the criterion in each of the groups shown in Table 1. RESULTS Extremely unhappy memories were more probable in the depresSed condition than in the elated condition. Extremely happy memories were more probable in the elated condition than in the depressed condition. Latency of retrieval showed a significant interaction between mood state and type of memory. Eflects of mood induction
Table 2 shows the effects of the elation and depressed mood inductions on the mood and counting-time measures. These results are based on the means from the three occasions of measurement following each mood induction. The results of dependent r-tests comparing these measures in the two conditions are also shown. The difference in d~pondency following the two mood inductions was, of course, guaranteed by the criterion used to select subjects. Following depressed mood induction subjects were also significantly more anxious, less happy and took longer to count from 1 to 10. ~i~re~tiuf
e@cts on pro~u~j~iry
of retriever
of~uppy
and unhappy
experiences
Table 2 shows the’ percentage of the memories retrieved which were rated as happy (-1-1, +2 or +3)or unhappy (-1, -2 or -3) in the two mood conditions. Because of the non-normality of the distributions sign-tests were used to compare the percentages in the two conditions. Happy memories were signifi~ntly more probable in the elation condition than in the depressed condition (Table 2), only 2 out of the 20 subjects showing the reverse pattern. Unhappy memories were more probable in the depressed condition but not significantly so. Table 2 also shows the percentage of the memories retrieved which were rated as pleasant (+ I, +2 or +3) or unpleasant (- 1, -2 or -3) in the two mood conditions. Both differences in percentages were in the same direction as for happy and unhappy memories, but neither was significant. Ratings of pleasantness and happiness of experiences were not always highIy related; the correlation between the two ratings for all memories was 0.70. WhiIe 91% of memories rated pleasant were also rated happy. 29% of
Elation-depression
and accessibility of memories
343
Table 2. Effects of elation and depression mood inductions Elation induction
Depression induction
M
M
Measure Despondency* Anxiety* Happiness* Counting time (s)t O0Happy memories ” (, Unhappy memories no Pleasant memories a” Unpleasant memories Latency happy memories (s)S Latency unhappy memories (s):
Statistic
p (2 tail)
r = 10.66 t = 2.20 r = 9.14 r = 2.29 sign test sign test sign test sign test
8.5 18.5 71.7 5.75 68.8 19.9 56.1 33.9
44.8 28.5 37.0 6.32 51.4 28.3 44.5 46.1
4.89
5.88
Tukey
0.06
6.09
5.39
Tukey
N.S.
N.B. n = 20 for each mean. * Mood measured on O-100 scales. t Time taken to count from 1 to 10. $ Latencies subjected to log transformation to normalise. Means for latencies calculated by antilogarithm from transformed data
memories rated unpleasant were rated happy also. This occurred because a number of subjects recalled experiences during which they had felt happy, although the experiences themselves they rated ‘objectively’ as unpleasant. An example of such an experience would be a camping weekend in which it had rained continuously, and the subject had been soaked through, but she had, nonetheless, enjoyed herself. Of 79 such experiences recalled, 47 were recalled in the elated condition and .32 in the depressed condition. As a significant effect of mood was only obtained on the happy-unhappy categorisation, further analysis was restricted to this dimension. Table 3 shows the percentage of memories at different happiness ratings in depressed and elated moods. The ratios of these percentages are shown graphically in Fig. 1. Extremely unhappy experiences were retrieved significantly more often in the depressed condition than in the elated condition, and extremely happy experiences were retrieved significantly more often in the elated condition than in the depressed condition. The marginally sign&ant difference in percentage of memories rated 0 probably simply reflects the fact that the excess of happy memories in the elated condition is not totally compensated by the excess of unhappy memories in the depressed condition. Some indication of the extent of the differential effect of mood on retrieval of happy and unhappy memories is the fact that while extremely happy memories are approximately eight times more probable than extremely unhappy memories in the elated condition, they are only approximately twice as probable in the depressed condition. Differential effects of mood on latency of retrieval oJ happy and unhappy memories
Mean latency of retrieval was calculated separately for happy memories and unhappy memories for each subject in each mood condition. The results are summarised in Table 2.
Table 3. Percentage of memories at different happiness ratings in depressed and elated moods Happiness rating no in elated mood (E) ’ in depressed mood (D) iatio E/D Significance of difference m “g E-D (sign test, 2-tail)
-3 3.6 8.9 0.40
-2 4.1 7.0 0.59
-1 12.2 12.3 0.99
p < 0.008
N.S.
N.S.
0 11.3 20.3 0.56
p
t-1 15.5 13.1 1.18
2+6.25 20.5 1.29
N.S.
N.S.
+3 26.8 17.8 1.51
p
JOHN D.
344
TEASDALE,
ROBERTTAYLOR
Happiness
Fig. 1. Ratio
and SARAH J.F~GARTV
rating
E/D for memories at different happiness ratings; E/D = O,, of memories mood at a given rating/% of memories in depressed mood at that rating.
in
elated
A 2 x 2 analysis of variance (elated-depressed mood x happy-unhappy memories) yielded no significant main effect for mood or type of memory, but a highly significant interaction between these two factors [F (1,19) = 10.09, p = 0.005]. The interaction, which is shown in Fig. 2, was examined by Tukey test. This showed that, within the elated condition. happy memories were recalled significantly faster (p < 0.05) than unhappy memories, and there was a tendency (p < 0.06) for happy memories to be recalled faster in the elated condition than in the depressed condition. Overall, unhappy memories were recalled non-significantly faster than happy memories within the depressed condition, and non-significantly faster in the depressed condition than in the elated condition. However, extremely unhappy memories (those rated - 3) were actually recalled nonsignificantly faster in the elated condition than in the depressed condition.
6.5 6.0
z 5.5 v ,' c 5.0 z '; ; 4.5 z I
4.0
-I ‘r
ol Elated
Depressed Mood
Fig.
2. Interaction
(p = 0.005) between mood induction (elation vs depression) memory (happy vs. unhappy) for latency of memory retrieval.
and
type
of
Elation-depression
and accessibility
of memories
345
Correlational analysis If the mood inductions have different effects on the probability of retrieval of happy and unhappy memories because of the differences in mood they produce, we would expect some relationship between the extent of the ditference in mood between the two conditions and the extent of differences in probability of retrieval. To examine this correlations were calculated for all the subjects tested between the differences in percentage of happy memories in the two conditions and the differences in mood. Significant correlations were obtained for the differences in mean despondency [r (41) = 0.46, p < 0.011, the differences in mean happiness [r (41) = -0.32, p < 0.051 and the differences in an overall measure of ‘bad mood’, calculated by adding the mean scores for despondency and anxiety and subtracting the mean score for happiness [r(41) = 0.37, p < 0.05]. The correlation for differences in mean anxiety [r (41) = 0.033 was not significant.
DISCUSSION The present finding that induced mood differentially affected the probability of retrieving memories of happy or unhappy past experiences confirms the generality of previous findings. Teasdale and Fogarty (1979) found differential effects of mood induction on the latency to recall such experiences, and Isen et al. (1978) found effects on the extent of recall of positive trait words previously learned in the experimental setting. Together, these results lend support to the notion that induced mood states modify the accessibility of different types of cognition. Teasdale and Fogarty (1979) and Isen et al. (1978) found the effects of mood restricted to the accessibility of positive cognitions, with little effect on negative cognitions. By contrast, the present study found effects on both positive and negative cognitions; extremely happy memories were more common in the elated than in the depressed mood, and extremely unhappy memories were more common in the depressed mood than in the elated mood. The first of these effects does not necessarily account for the second. although, of course, there would necessarily be some interdependence between the percentage of memories at different happiness ratings as they all had to add up to 1009;. The effects of mood on latency measures in this study were, as in our previous study (Teasdale and Fogarty, 1979) more apparent for positive memories. Indeed, although extremely unhappy memories were retrieved significantly more often in the depressed mood than in the elated mood, their latency of retrieval was nonsignificantly faster in the elated condition. Thus, in the present paradigm, latency and probability of retrieval do not appear to be equivalent measures of accessibility for extremely negative cognitions. Further, while effects of mood on the probability of recalling negative cognitions could be demonstrated in the present paradigm, the same was not true in the paradigm studied by Isen et al. (1978). The reasons for this are not clear. In the present study a significant effect on probability for negative cognitions was only obtained for memories of past real-life experiences rated as extremely unhappy. By contrast, the negative cognitions studied by Isen et al. (1978) were ,negative personality trait words forming parts of word lists learned in the experimental session. As in our previous study (Teasdale and Fogarty, 1979) the observed differences in accessibility of cognitions following the two mood inductions could have resulted either from differences in the mood induced or directly from differences in the mood induction procedures. In both studies, correlational evidence showed significant covariation across subjects between the extent to which mood actually differed in the two conditions and the extent of differences in accessibility of cognitions. As all subjects received the same induction procedures this evidence supports the idea that the differences in accessibility actually resulted from differences in mood. However, such correlational evidence cannot reject the alternative explanation. For example, subjects might vary in the extent ‘to which the mood induction self-statements generated thoughts of specific happy or unhappy past experiences. to the class of memories pattern of correlations.
Such thoughts might both affect mood and prime accessibility of similar past experiences. This could lead to the observed
346
JOHN D. TEASDALE. ROBERT TAYLOR and SARAH J. FIXARTY
If mood as such does, in fact, differentially modify the accessibility of different types of cognition, how does this occur? In discussing our previous results (Teasdale and Fogarty. 1979) we considered the possibility that this was an example of context-specific encoding and retrieval in which mood state acted as a context. This would suggest that memories of positive experiences would be more likely to be recalled in the elated mood because mood state at retrieval was similar to the happy mood state prevailing when the memory was encoded. For similar reasons, memories of negative experiences would be more likely to be recalled in the depressed mood state as this would approximate more closely the initial context in which they were encoded. The somewhat different results obtained for ratings of pleasantness-unpleasantness and happiness-unhappiness in the present study are interesting in this respect. Happiness ratings appeared to be the more important. When an experience was ‘objectively’ rated as unpleasant but the prevailing subjective state at encoding was happy the initial mood state appeared to be the better predictor of subsequent retrieval in various mood states. This finding. if reliable, would support the mood-dependent context-specific encoding and retrieval explanation. Our present findings suggest quite a marked effect of induced mood state on the probability of recalling happy as compared to unhappy cognitions. If we can assume that clinical mood states have similar effects on the probability of naturally occurring thoughts there are important implications for our understanding and treatment of these disorders. We have already discussed these elsewhere (Teasdale and Fogarty, 1979). The most important implication is that there may be a reciprocal relationship between cognition and emotion. Cognitive models of depression and other emotional disorders (e.g. Beck, 1976) propose that cognitions with particular content lead to emotional states. Our findings suggest that these states may then selectively increase the likelihood of cognitions of the type likely to perpetuate them and selectively decrease the likelihood of cognitions of the type likely to modify them. It is possible that in certain circumstances such a reciprocal relationship might lead to self-maintaining emotional states. Where this occurs therapy might then usefully aim to correct such a biasing effect of mood state on cognitive accessibility (e.g. Beck. 1976). Acknowledgements-This research was supported by the Medical Research The authors are very grateful to Donald E. Broadbent for helpful comments
Council of the United Kingdom. on an earlier draft of this article.
REFERENCES BECK A. T. (1967) Depression: Clinical. Experimental and Theoretical Aspeers. Harper and Row. New York. BECK A. T. (1976) Cognitive Therapy and rhe Emotional Disorders. International Universities Press. New York. EYSENCK H. J. and EYSENCK S. B. G. (1964) Manual of the Eysenck Personaliry Inrenrorv. University of London Press, London. ISEN A. M., SHALKER T. E., CLARK M. and KARP L. (1978) Affect. accessibility of material in memory. and behavior: a cognitive loop? J. Personalirg sot. Psycho/. 36. l-12. LLOYD G. G. and LISHMAN W. A. (1975) ERect of depression on the speed of recall of pleasant and unpleasant experiences. Psycho/. Med. 5, 173-180. SZABADI E., BRADSHAW C. M. and BES~N J. A. 0. (1976) Elongation of pause-time in speech: a simple. objective measure of motor retardation in depression. Br. J. Psychiar. 129. 592-597. TEASDALE J. D. and FCIGARTY S. J. (1979) Differential effects of induced mood on retrieval of pleasant and unpleasant memories from episodic memory. J. abnorm. Psychof. 88, 248-257. TEASDALE J. D., F~GARTY S. J. and WILLIAMS J. M. G. Speech rate as a measure of short-term variation m depression. In press. &if. J. Sot. Clin. Psychol. VELTEN E. (1968) A laboratory task for inductionof mood states. Behar. Res. Ther. 6. 473482. WINER B. J. (1962) Srarisricol Principles in Experimental Design. McGraw-Hill. New York.