psycho pharmacology
Psychopharmacology52, 223 226 (1977)
9 by Springer-Verlag1977
Effects of Cigarette Smoking on Incidental Memory KARIN ANDERSSON and G. ROBERT J. HOCKEY* Department of Psychology,Universityof Stockholm,Sweden
Abstract. The effects of cigarette-smoking in an im-
mediate memory task were studied in two groups of 25 female students (habitual smokers) tested either under a control (no smoking) condition or after smoking one cigarette. The memory task, requiring immediate serial recall of eight words, showed no differences between the two groups. Subjects were, however, also tested on recall of the position of words on the screen (each word could appear in any of the four corners). On this measure of incidental recall, the non-smoking group was far superior to the smoking group. This finding is in agreement with results obtained with noise-induced arousal and with the view that attentional selectivity is greater during increased arousal. K e y words." Cigarette smoking -
Arousal -
Free
recall - Incidental memory.
Smoking a cigarette leads to a state that is generally associated with increased arousal, and nicotine in normal smoking doses clearly acts as a stimulant on the central nervous system (Goodman and Gilman, 1966). It may thus be possible to manipulate the level of arousal by having subjects smoke or not, and in a series of investigations in our laboratory cigaretteinduced arousal, as measured by heart rate and adrenaline excretion, has been related to verbal rote learning and retention (Andersson and Post, 1974; Andersson, 1975a). The results, showing disruptive effects of cigarette smoking on immediate recall and a tendency towards improved delayed recall, are in line with those obtained using noise-induced arousal in paired-associate tasks (Berlyne et al., 1965; McLean, 1969) and *
Present address: DurhamUniversity,England
with data from paired-associate tasks where increased arousal has been inferred from larger GSR responses to particular stimulus words (Kleinsmith and Kaplan, 1963, 1964; Walker and Tarte, 1963). Smoking has further been shown to facilitate performance on a complex memory task requiring simultaneous dealing with a variety of cues when the initial arousal level was low. A high initial arousal level seemed, however, to negatively influence performance on the task (Andersson, 1975b). The results further indicated an inverted-U relationship between arousal, as measured by heart rate, and performance on the task. These additional findings were interpreted in terms of Easterbrook's theory (1959) proposing a narrowing of the attentional field with increased arousal. In the present experiment the effect of smoking on attention was examined further by using a somewhat different kind of memory task, involving incidental learning. Hockey and Hamilton (1970) showed that noise-induced arousal did not affect recall of a single eight-item word list, but impaired recall of the 'irrelevant' location of the words on each of the stimulus slides. Davies and Jones (1975) have recently replicated this finding, for both noise and monetary incentive. These results are consistent with the demonstration that noise causes an increase in selectivity in visual monitoring, biasing attention more towards important activities (Hockey, 1970). Hamilton et al. (1972), in fact showed that the impaired immediate recall observed in paired-associate tasks only occurs when the order of the S-R pairs is varied from trial to trial. This suggests a stronger attention to order information in noise, a strategy which is, of course, maladaptive in such a situation. Since smoking is seen to affect recall processes in generally similar ways to noise in the above studies, it is clearly necessary to examine the extent of this similarity, if we are to generalize effectively from accumulated findings. In particular, does smoking also
224 p r o d u c e a m o r e selective p a t t e r n o f a t t e n t i o n in the incidental l e a r n i n g t a s k o f H o c k e y a n d H a m i l t o n (1970)? I f so, we clearly have a s t r o n g e r basis for suggesting a c o m m o n process o f a r o u s a l u n d e r l y i n g the effects o f these two stressors. T h e t a s k used was identical to t h a t e m p l o y e d in the H o c k e y a n d H a m i l t o n study, r e l e v a n t cues being w o r d s to be recalled in c o r r e c t o r d e r a n d the irrelevant cue being the l o c a t i o n o f each w o r d (which c o u l d a p p e a r in a n y o f the f o u r c o r n e r s o f the screen, a n d a b o u t w h i c h subjects received no instructions). I n a d d i t i o n , we p r e s e n t e d the list a s e c o n d time to o b t a i n s o m e further i n f o r m a t i o n a b o u t a n y c h a n g e s in strategy d u e to subjects being m a d e a w a r e o f the irrelevant cue.
METHODS
Subjects, Design, and Procedure Fifty female university students (all habitual smokers) participated in the experiment. They were tested under either smoking or non-smoking conditions (25 subjects in each) in small sub-groups of two or three subjects. The ages of the smoking group ranged from 21-33 years (mean 26 years) and the body weights from 4 6 - 67 kg (mean 58 kg). The ages of the non-smoking group ranged from 19-39 years (mean 25 years) and the body weights from 49-75 kg (mean 57 kg). Daily consumption of cigarettes varied from 4 - 2 5 (mean 13) for the smoking group and from 7-23 (mean 13) for the non-smoking group. The experimental sessions took place before 11.00 a.m. and lasted about 20 min. The subjects were told in advance to refrain from smoking and drinking coffee on the morning of the session. After a period of 10 min rest, each session began with the measurement of heart rate, whereafter the subjects smoked one cigarette in the smoking sessions or relaxed for the corresponding 7 rain in the non-smoking session. Heart rate was again measured and subjects then carried out the memory task. A final heart rate measure was taken after the test.
Cigarette Smoking The standard cigarette used was a filter cigarette of the Virginia King brand, containing 2.3 mg nicotine (according to current information from the Swedish Tobacco Company).
Psychopharmacology 52 (1977) Thereafter the second series of words was shown to the subjects, but on this occassion they were informed to attend both to the words in their correct order and to their location on the screen.
Heart Rate Heart rate was recorded by palpation of the radial artery. Measurements were made at the beginning of each session, immediately after smoking (or corresponding pause) and at the end of the session.
RESULTS
Memo~7 Task Scoring. P e r f o r m a n c e on the m e m o r y t a s k was scored b y c o n s i d e r i n g (1) strict o r d e r e d recall o f w o r d s , (2) w o r d s recalled irrespective o f order, a n d (3) recall o f l o c a t i o n for c o r r e c t l y r e p o r t e d w o r d s (the d a t a are given in T a b l e 1).
List 1. Relevant Cues. N e i t h e r o f the m e a s u r e s (1) a n d (2) s h o w significant differences between the s m o k ing a n d n o n - s m o k i n g groups. Scores are n e a r l y identical in the two c o n d i t i o n s .
Irrelevant Cues. T a b l e 1 shows p e r f o r m a n c e o n the irrelevant t a s k (the n u m b e r o f correct l o c a t i o n s as a p e r c e n t a g e o f the t o t a l n u m b e r o f w o r d s correctly recalled). T h e irrelevant l o c a t i o n s were recalled signific a n t l y less well by the s m o k i n g g r o u p (t = 2.09, df = 48, P < 0.05), their p e r f o r m a n c e being o n l y slightly a b o v e the c h a n c e level o f 25 %. List 2. M e a n s a n d s t a n d a r d errors for the three perf o r m a n c e m e a s u r e s d e s c r i b e d a b o v e are again given in T a b l e 1. T h e general picture is t h a t there were only small v a r i a t i o n s b e t w e e n g r o u p s with r e g a r d to percentage o f correctly recalled w o r d s b o t h w h e n o r d e r a c c u r a c y was c o n s i d e r e d a n d not. Likewise there were no consistent differences between g r o u p s on the l o c a t i o n task, t h o u g h the s m o k i n g g r o u p n o w shows a non-significant advantage on this measure.
Memory Task
Incidental Versus Intentional Memory
Two series of eight common bisyllabic Swedish adjectives were used. The words were projected one at a time by a slide projector at a fixed rate of one every two seconds. Each word could appear in any of the four corners of the screen. No successive slides presented words in the same location. Before the first series of words was presented to the subjects they were told that they should write down the words in the correct order upon termination of the series. They were told nothing in advance about the location cue. After this relevant task had been performed, it was pointed out that each word had in fact appeared in different corners of the screen, and subjects were asked to indicate these locations by putting a cross in the corresponding corner for each word they had written down.
C o m p a r i s o n s b e t w e e n the two lists w i t h r e g a r d to the different p e r f o r m a n c e scores (Table 1) show t h a t the p e r c e n t a g e o f c o r r e c t l y recalled w o r d s irrespective o f o r d e r d e c r e a s e d f r o m the first to the s e c o n d list in b o t h the s m o k i n g a n d the n o n - s m o k i n g g r o u p , a l t h o u g h the decline was significant only for the f o r m e r (t = 2.75, d f = 48, P < 0.05). W h e n o r d e r a c c u r a c y is t a k e n into a c c o u n t the reverse p a t t e r n is seen, p e r f o r m a n c e i m p r o v i n g f r o m List I to List 2. This difference a p p r o a c h e s a significant value (t = 1.84, d f = 48, P < 0.10) for the s m o k i n g g r o u p .
K. Andersson and G. R. J. Hockey : Effects of Cigarette Smoking on Incidental Memory
225
Table 1. Means and standard errors of performance measures in the smoking and non-smoking conditions Measure
Non-smoking
Smoking M
SE
M
SE
Percentage of words recalled in correct order
List 1 List 2
37.2 45.8
2.2 2.8
37.2 44.2
2.0 3.6
Percentage of words recalled irrespective of order
List 1 List 2
66.2 56.8
2.0 2.6
64.8 59.3
2.3 2.8
Percentage of correct locations of the total number of recalled words
List 1 List 2
30.2 62.2
3.7 4.8
46.5 55.3
4.2 3.8
Table 2. Heart rate before and after the smoking and non-smoking pause respectivelyin the smoking and non-smoking condition Smoking
Non-smoking
M
SE
M
SE
Before treatment
74.24
2.42
79.48
2.96
After treatment
88.92
2.58
79.08
2.57
Location recall scores were, of course, increased in both conditions from the first to the second list, though the improvement was again significant only for the smoking group (t = 3.67, df = 48, P < 0.01).
Heart Rate Table 2 shows mean heart rate before and after the smoking and non-smoking pause respectively. H e a r t rate increased significantly after smoking (t = 4.88, d f = 48, P < 0.001), while almost no changes in heart rate occurred in the non-smoking group.
DISCUSSION The present data suggest that cigarette smoking reduces the subjects' attention to 'irrelevant' information. These effects are similar to those found with noise-induced arousal in this kind of task (Hockey and Hamilton, 1970; Davies and Jones, 1975). Hockey and Hamilton (1970) showed, in addition, that the utilization of order cues was more pronounced during noise, a result which was not obtained in the Davies and Jones study, nor as a corresponding effect of smoking in the current experiment. This finding is likely to depend rather heavily on the way subjects interpret instructions to guess if they are not sure of the correct order, but it is evident also in the Hamilton et al. (1972) experiment reported earlier. Nevertheless,
while we clearly want to suggest a c o m m o n basis of increased arousal for the attentional effects of smoking and noise in this task (and also monetary incentives in the Davies and Jones study), it is still conceivable that the individual stressors differ somewhat in their effects on recall strategy, or other component processes. This possibility has yet to be explored systematically. The data from the second list administration do not lead to any firm inferences. However, it is interesting to note that the change in instructions, which could be regarded as drawing the subjects' attention relatively more strongly towards the location cue, actually seems to give a reversal of the pattern of performance observed in List 1. Locations are now recalled rather better in the smoking condition, while unordered word recall is a little worse, the opposite direction of differences to those seen in List 1. AI: though it is difficult to deduce much f r o m these casual observations, this is precisely the sort of change one would expect if locations were now perceived as being in some sense more important (as might result from the novelty value of this feature of the task), and the words less important. Such a change of strategy would, however, not be found with all subjects, and the overall differences would be small and non-significant, as is generally the case for List 2 comparisons. The present data, then, extend the area of c o m m o n ground between smoking and noise, and it seems parsimonious to propose an arousal process as being involved in the mediation of the effects of both kinds of stressors. They are also in agreement with clinical studies showing that increased emotional arousal, anxiety, and stress (see the extensive review by Korchin, 1964) lead to a more limited and focused attention. In this context it is also interesting to note that tobacco smoking increases the rate of habituation, which generally is assumed to reflect an individual's ability to 'block out' irrelevant information (Friedm a n et al., 1974).
226
Acknowledgements. This report was supported by a grant from the Swedish Tobacco Company (Project No. 7505) and by a grant to Professor Marianne Frankenhaeuser from the Swedish Medical Research Council (Project No. 997). I wish to thank Mrs. Annika Wahlstr6m-Wottle for assistance in collecting and calculating data.
REFERENCES Andersson, K. : Effects of cigarette smoking on learning and retention. Psychopharmacologia (Bed.) 41, 1 - 5 (1975a) Andersson, K. : Cigarette smoking, arousal and performance in a complex memory task. Rep. Dep. Psychol., Univ. Stockholm, No. 454 (1975b) Andersson, K., Post, B.: Effects of cigarette smoking on verbal rote learning and physiological arousal. Scand. J. Psychol. 15, 2 6 3 - 267 (1974) Berlyne, D. E., Borsa, D. M., Craw, M. A., Gelman, R. S., Mandell, E. E. : Effects of stimulus complexity and induced arousal on paired-associate learning. J. Verb. Learn. Verb. Behav. 4, 291-299 (1965) Davies, D. R., Jones, D. M. : The effects of noise and incentives upon attention in short-term memory. Brit. J. Psychol. 66, 61 - 68 (1975) Easterbrook, J. A. : The effect of emotion on cue utilization and the organization of behavior. Psychol. Rev. 66, 1 8 3 - 201 (1959)
Psychopharmacology 52 (1977) Friedman, J., Horwath, T., Meares, R.: Tobacco smoking and a 'stimulus barrier'. Nature (Lond.) 248, 455-456 (1974) Goodman, L. S., Gilman, A. : The Pharmacological Basis of Therapeutics, 3rd edition. New York: MacMillan 1966 Hamilton, P., Hockey, G. R. J., Quinn, J. G.: Information selection, arousal and memory. Brit. J. Psychol. 63, 181-189 (1972) Hockey, G. R. J. : Effect of loud noise on attentional selectivity. Quart. J. exp. Psychol. 22, 2 8 - 3 6 (1970) Hockey, G. R. J., Hamilton, P. : Arousal and information selection in short term memory. Nature (Lond.) 226, 866-867 (1970) Kleinsmith, L. J., Kaplan, S. : Paired associates learning as a function of arousal and interpolated interval. J. exp. Psychot. 65, 190-193 (1963) Kleinsmith, L. J., Kaplan, S. : The interaction of arousal and recall interval in nonsense syllable paired associates learning. J. exp. Psychol. 67, 124-126 (1964) Korchin, S.J.: Anxiety and cognition. In: Cognition: Theory, research, promise, C. Scheerer, ed., pp. 58-78. New York: Harper Row 1964 McLean, P. D. : Induced arousal and time of recall as determinants of paired-associate recall. Brit. J. Psychol. 60, 5 7 - 6 2 (1969) Walker, E. L., Tarte, R. : Memory storage as a function of arousal and time with homogeneous and heterogeneous lists. J. Verb. Learn. Verb. Behav. 2, 113-119 (1963)
Received October 19, 1976
Psychopharmacology52, 223 226 (1977)
9 by Springer-Verlag1977
Effects of Cigarette Smoking on Incidental Memory KARIN ANDERSSON and G. ROBERT J. HOCKEY* Department of Psychology,Universityof Stockholm,Sweden
Abstract. The effects of cigarette-smoking in an im-
mediate memory task were studied in two groups of 25 female students (habitual smokers) tested either under a control (no smoking) condition or after smoking one cigarette. The memory task, requiring immediate serial recall of eight words, showed no differences between the two groups. Subjects were, however, also tested on recall of the position of words on the screen (each word could appear in any of the four corners). On this measure of incidental recall, the non-smoking group was far superior to the smoking group. This finding is in agreement with results obtained with noise-induced arousal and with the view that attentional selectivity is greater during increased arousal. K e y words." Cigarette smoking -
Arousal -
Free
recall - Incidental memory.
Smoking a cigarette leads to a state that is generally associated with increased arousal, and nicotine in normal smoking doses clearly acts as a stimulant on the central nervous system (Goodman and Gilman, 1966). It may thus be possible to manipulate the level of arousal by having subjects smoke or not, and in a series of investigations in our laboratory cigaretteinduced arousal, as measured by heart rate and adrenaline excretion, has been related to verbal rote learning and retention (Andersson and Post, 1974; Andersson, 1975a). The results, showing disruptive effects of cigarette smoking on immediate recall and a tendency towards improved delayed recall, are in line with those obtained using noise-induced arousal in paired-associate tasks (Berlyne et al., 1965; McLean, 1969) and *
Present address: DurhamUniversity,England
with data from paired-associate tasks where increased arousal has been inferred from larger GSR responses to particular stimulus words (Kleinsmith and Kaplan, 1963, 1964; Walker and Tarte, 1963). Smoking has further been shown to facilitate performance on a complex memory task requiring simultaneous dealing with a variety of cues when the initial arousal level was low. A high initial arousal level seemed, however, to negatively influence performance on the task (Andersson, 1975b). The results further indicated an inverted-U relationship between arousal, as measured by heart rate, and performance on the task. These additional findings were interpreted in terms of Easterbrook's theory (1959) proposing a narrowing of the attentional field with increased arousal. In the present experiment the effect of smoking on attention was examined further by using a somewhat different kind of memory task, involving incidental learning. Hockey and Hamilton (1970) showed that noise-induced arousal did not affect recall of a single eight-item word list, but impaired recall of the 'irrelevant' location of the words on each of the stimulus slides. Davies and Jones (1975) have recently replicated this finding, for both noise and monetary incentive. These results are consistent with the demonstration that noise causes an increase in selectivity in visual monitoring, biasing attention more towards important activities (Hockey, 1970). Hamilton et al. (1972), in fact showed that the impaired immediate recall observed in paired-associate tasks only occurs when the order of the S-R pairs is varied from trial to trial. This suggests a stronger attention to order information in noise, a strategy which is, of course, maladaptive in such a situation. Since smoking is seen to affect recall processes in generally similar ways to noise in the above studies, it is clearly necessary to examine the extent of this similarity, if we are to generalize effectively from accumulated findings. In particular, does smoking also
224 p r o d u c e a m o r e selective p a t t e r n o f a t t e n t i o n in the incidental l e a r n i n g t a s k o f H o c k e y a n d H a m i l t o n (1970)? I f so, we clearly have a s t r o n g e r basis for suggesting a c o m m o n process o f a r o u s a l u n d e r l y i n g the effects o f these two stressors. T h e t a s k used was identical to t h a t e m p l o y e d in the H o c k e y a n d H a m i l t o n study, r e l e v a n t cues being w o r d s to be recalled in c o r r e c t o r d e r a n d the irrelevant cue being the l o c a t i o n o f each w o r d (which c o u l d a p p e a r in a n y o f the f o u r c o r n e r s o f the screen, a n d a b o u t w h i c h subjects received no instructions). I n a d d i t i o n , we p r e s e n t e d the list a s e c o n d time to o b t a i n s o m e further i n f o r m a t i o n a b o u t a n y c h a n g e s in strategy d u e to subjects being m a d e a w a r e o f the irrelevant cue.
METHODS
Subjects, Design, and Procedure Fifty female university students (all habitual smokers) participated in the experiment. They were tested under either smoking or non-smoking conditions (25 subjects in each) in small sub-groups of two or three subjects. The ages of the smoking group ranged from 21-33 years (mean 26 years) and the body weights from 4 6 - 67 kg (mean 58 kg). The ages of the non-smoking group ranged from 19-39 years (mean 25 years) and the body weights from 49-75 kg (mean 57 kg). Daily consumption of cigarettes varied from 4 - 2 5 (mean 13) for the smoking group and from 7-23 (mean 13) for the non-smoking group. The experimental sessions took place before 11.00 a.m. and lasted about 20 min. The subjects were told in advance to refrain from smoking and drinking coffee on the morning of the session. After a period of 10 min rest, each session began with the measurement of heart rate, whereafter the subjects smoked one cigarette in the smoking sessions or relaxed for the corresponding 7 rain in the non-smoking session. Heart rate was again measured and subjects then carried out the memory task. A final heart rate measure was taken after the test.
Cigarette Smoking The standard cigarette used was a filter cigarette of the Virginia King brand, containing 2.3 mg nicotine (according to current information from the Swedish Tobacco Company).
Psychopharmacology 52 (1977) Thereafter the second series of words was shown to the subjects, but on this occassion they were informed to attend both to the words in their correct order and to their location on the screen.
Heart Rate Heart rate was recorded by palpation of the radial artery. Measurements were made at the beginning of each session, immediately after smoking (or corresponding pause) and at the end of the session.
RESULTS
Memo~7 Task Scoring. P e r f o r m a n c e on the m e m o r y t a s k was scored b y c o n s i d e r i n g (1) strict o r d e r e d recall o f w o r d s , (2) w o r d s recalled irrespective o f order, a n d (3) recall o f l o c a t i o n for c o r r e c t l y r e p o r t e d w o r d s (the d a t a are given in T a b l e 1).
List 1. Relevant Cues. N e i t h e r o f the m e a s u r e s (1) a n d (2) s h o w significant differences between the s m o k ing a n d n o n - s m o k i n g groups. Scores are n e a r l y identical in the two c o n d i t i o n s .
Irrelevant Cues. T a b l e 1 shows p e r f o r m a n c e o n the irrelevant t a s k (the n u m b e r o f correct l o c a t i o n s as a p e r c e n t a g e o f the t o t a l n u m b e r o f w o r d s correctly recalled). T h e irrelevant l o c a t i o n s were recalled signific a n t l y less well by the s m o k i n g g r o u p (t = 2.09, df = 48, P < 0.05), their p e r f o r m a n c e being o n l y slightly a b o v e the c h a n c e level o f 25 %. List 2. M e a n s a n d s t a n d a r d errors for the three perf o r m a n c e m e a s u r e s d e s c r i b e d a b o v e are again given in T a b l e 1. T h e general picture is t h a t there were only small v a r i a t i o n s b e t w e e n g r o u p s with r e g a r d to percentage o f correctly recalled w o r d s b o t h w h e n o r d e r a c c u r a c y was c o n s i d e r e d a n d not. Likewise there were no consistent differences between g r o u p s on the l o c a t i o n task, t h o u g h the s m o k i n g g r o u p n o w shows a non-significant advantage on this measure.
Memory Task
Incidental Versus Intentional Memory
Two series of eight common bisyllabic Swedish adjectives were used. The words were projected one at a time by a slide projector at a fixed rate of one every two seconds. Each word could appear in any of the four corners of the screen. No successive slides presented words in the same location. Before the first series of words was presented to the subjects they were told that they should write down the words in the correct order upon termination of the series. They were told nothing in advance about the location cue. After this relevant task had been performed, it was pointed out that each word had in fact appeared in different corners of the screen, and subjects were asked to indicate these locations by putting a cross in the corresponding corner for each word they had written down.
C o m p a r i s o n s b e t w e e n the two lists w i t h r e g a r d to the different p e r f o r m a n c e scores (Table 1) show t h a t the p e r c e n t a g e o f c o r r e c t l y recalled w o r d s irrespective o f o r d e r d e c r e a s e d f r o m the first to the s e c o n d list in b o t h the s m o k i n g a n d the n o n - s m o k i n g g r o u p , a l t h o u g h the decline was significant only for the f o r m e r (t = 2.75, d f = 48, P < 0.05). W h e n o r d e r a c c u r a c y is t a k e n into a c c o u n t the reverse p a t t e r n is seen, p e r f o r m a n c e i m p r o v i n g f r o m List I to List 2. This difference a p p r o a c h e s a significant value (t = 1.84, d f = 48, P < 0.10) for the s m o k i n g g r o u p .
K. Andersson and G. R. J. Hockey : Effects of Cigarette Smoking on Incidental Memory
225
Table 1. Means and standard errors of performance measures in the smoking and non-smoking conditions Measure
Non-smoking
Smoking M
SE
M
SE
Percentage of words recalled in correct order
List 1 List 2
37.2 45.8
2.2 2.8
37.2 44.2
2.0 3.6
Percentage of words recalled irrespective of order
List 1 List 2
66.2 56.8
2.0 2.6
64.8 59.3
2.3 2.8
Percentage of correct locations of the total number of recalled words
List 1 List 2
30.2 62.2
3.7 4.8
46.5 55.3
4.2 3.8
Table 2. Heart rate before and after the smoking and non-smoking pause respectivelyin the smoking and non-smoking condition Smoking
Non-smoking
M
SE
M
SE
Before treatment
74.24
2.42
79.48
2.96
After treatment
88.92
2.58
79.08
2.57
Location recall scores were, of course, increased in both conditions from the first to the second list, though the improvement was again significant only for the smoking group (t = 3.67, df = 48, P < 0.01).
Heart Rate Table 2 shows mean heart rate before and after the smoking and non-smoking pause respectively. H e a r t rate increased significantly after smoking (t = 4.88, d f = 48, P < 0.001), while almost no changes in heart rate occurred in the non-smoking group.
DISCUSSION The present data suggest that cigarette smoking reduces the subjects' attention to 'irrelevant' information. These effects are similar to those found with noise-induced arousal in this kind of task (Hockey and Hamilton, 1970; Davies and Jones, 1975). Hockey and Hamilton (1970) showed, in addition, that the utilization of order cues was more pronounced during noise, a result which was not obtained in the Davies and Jones study, nor as a corresponding effect of smoking in the current experiment. This finding is likely to depend rather heavily on the way subjects interpret instructions to guess if they are not sure of the correct order, but it is evident also in the Hamilton et al. (1972) experiment reported earlier. Nevertheless,
while we clearly want to suggest a c o m m o n basis of increased arousal for the attentional effects of smoking and noise in this task (and also monetary incentives in the Davies and Jones study), it is still conceivable that the individual stressors differ somewhat in their effects on recall strategy, or other component processes. This possibility has yet to be explored systematically. The data from the second list administration do not lead to any firm inferences. However, it is interesting to note that the change in instructions, which could be regarded as drawing the subjects' attention relatively more strongly towards the location cue, actually seems to give a reversal of the pattern of performance observed in List 1. Locations are now recalled rather better in the smoking condition, while unordered word recall is a little worse, the opposite direction of differences to those seen in List 1. AI: though it is difficult to deduce much f r o m these casual observations, this is precisely the sort of change one would expect if locations were now perceived as being in some sense more important (as might result from the novelty value of this feature of the task), and the words less important. Such a change of strategy would, however, not be found with all subjects, and the overall differences would be small and non-significant, as is generally the case for List 2 comparisons. The present data, then, extend the area of c o m m o n ground between smoking and noise, and it seems parsimonious to propose an arousal process as being involved in the mediation of the effects of both kinds of stressors. They are also in agreement with clinical studies showing that increased emotional arousal, anxiety, and stress (see the extensive review by Korchin, 1964) lead to a more limited and focused attention. In this context it is also interesting to note that tobacco smoking increases the rate of habituation, which generally is assumed to reflect an individual's ability to 'block out' irrelevant information (Friedm a n et al., 1974).
226
Acknowledgements. This report was supported by a grant from the Swedish Tobacco Company (Project No. 7505) and by a grant to Professor Marianne Frankenhaeuser from the Swedish Medical Research Council (Project No. 997). I wish to thank Mrs. Annika Wahlstr6m-Wottle for assistance in collecting and calculating data.
REFERENCES Andersson, K. : Effects of cigarette smoking on learning and retention. Psychopharmacologia (Bed.) 41, 1 - 5 (1975a) Andersson, K. : Cigarette smoking, arousal and performance in a complex memory task. Rep. Dep. Psychol., Univ. Stockholm, No. 454 (1975b) Andersson, K., Post, B.: Effects of cigarette smoking on verbal rote learning and physiological arousal. Scand. J. Psychol. 15, 2 6 3 - 267 (1974) Berlyne, D. E., Borsa, D. M., Craw, M. A., Gelman, R. S., Mandell, E. E. : Effects of stimulus complexity and induced arousal on paired-associate learning. J. Verb. Learn. Verb. Behav. 4, 291-299 (1965) Davies, D. R., Jones, D. M. : The effects of noise and incentives upon attention in short-term memory. Brit. J. Psychol. 66, 61 - 68 (1975) Easterbrook, J. A. : The effect of emotion on cue utilization and the organization of behavior. Psychol. Rev. 66, 1 8 3 - 201 (1959)
Psychopharmacology 52 (1977) Friedman, J., Horwath, T., Meares, R.: Tobacco smoking and a 'stimulus barrier'. Nature (Lond.) 248, 455-456 (1974) Goodman, L. S., Gilman, A. : The Pharmacological Basis of Therapeutics, 3rd edition. New York: MacMillan 1966 Hamilton, P., Hockey, G. R. J., Quinn, J. G.: Information selection, arousal and memory. Brit. J. Psychol. 63, 181-189 (1972) Hockey, G. R. J. : Effect of loud noise on attentional selectivity. Quart. J. exp. Psychol. 22, 2 8 - 3 6 (1970) Hockey, G. R. J., Hamilton, P. : Arousal and information selection in short term memory. Nature (Lond.) 226, 866-867 (1970) Kleinsmith, L. J., Kaplan, S. : Paired associates learning as a function of arousal and interpolated interval. J. exp. Psychot. 65, 190-193 (1963) Kleinsmith, L. J., Kaplan, S. : The interaction of arousal and recall interval in nonsense syllable paired associates learning. J. exp. Psychol. 67, 124-126 (1964) Korchin, S.J.: Anxiety and cognition. In: Cognition: Theory, research, promise, C. Scheerer, ed., pp. 58-78. New York: Harper Row 1964 McLean, P. D. : Induced arousal and time of recall as determinants of paired-associate recall. Brit. J. Psychol. 60, 5 7 - 6 2 (1969) Walker, E. L., Tarte, R. : Memory storage as a function of arousal and time with homogeneous and heterogeneous lists. J. Verb. Learn. Verb. Behav. 2, 113-119 (1963)
Received October 19, 1976
