Running Head: DOES SMOKING AFFECT INTRUSIVE THINKING?

Does Smoking Affect Intrusive 1

Running head: DOES SMOKING AFFECT INTRUSIVE THINKING?

Does Smoking Affect Intrusive Thinking?

Kelly Carrier

North Carolina State University Does Smoking Affect Intrusive 2

Abstract

The relationship between smoking and ability to suppress intrusive thoughts was examined in this study. The correlation between smoking and negative affect was also reviewed. Participants included a nonsmoking group and smokers who were either asked to smoke prior to the study or refrain for one hour. Participants wrote about a coatrack for three minutes, followed by three minutes of suppression of the coatrack. Upon completion of this task, this three minute expression and suppression period was repeated in regard to a negative experience. The study revealed when self reported nicotine dependence was taken into account as a covariate, the type of suppression target (neutral or negative) appeared to differ between the two smoking groups. Furthermore, the study also indicated that individuals high on negative affect also scored higher on other measures, such as suppression failures, self reported intrusive thoughts, and number of cigarettes smoked per day. Does Smoking Affect Intrusive 3

The Nicotine Link To Intrusive Thoughts

Nicotine is a pervasive influence affecting many qualities of life, both physical and psychological, of approximately 30% of the United States- or 71.5 million people- who are smokers. Being such a substantial percentage of the population, smoking is an area that has been heavily investigated to determine various psychological effects that it may have on smokers’ lives. Of particular interest to this study are the many cognitive factors that have been explored in regard to nicotine use, which appears to improve certain aspects of cognition while hindering others. For example, nicotine is thought to improve certain cognitive resources such as short-term memory and performance accuracy (Grobe, 1998), as well as reaction times in smokers (Ernst, 2001). However, it has also been found to have high cognitive costs in other areas. Nicotine depletes mental resources such as attention and causes an inability to inhibit information that is related to smoking related stimuli (Zwaan, 2000). While nicotine has generally been thought to hinder attention, research has shown that in situations where attention is low, as in cases of ADHD, nicotine facilitates attention. (Potter, 2004) However, Kassel (1997) suggests that nicotine actually enhances selective attention and improves one’s ability to filter irrelevant stimuli. Nicotine may have different effects on certain groups than expected in general circumstances and on different types of attention.

Other resources such as working memory seem to produce more varied results.

While it is thought by some that nicotine enhances working memory (Pineda, 1998), others dispute this theory, stating that nicotine hampers working memory (Ernst, 2001;

Madden, 2001). Nicotine also hinders spatial working memory, as reported by Park,

Knopick, McGurk, et al. (2000), also suggesting that perhaps the effect of nicotine may Does Smoking Affect Intrusive 4 vary depending on the specific component of working memory or cognition in question.

While the application of this research to humans is mixed, recent research involving rats indicate an improvement in working memory upon receiving a dose of nicotine and appears consistent in the literature (Attaway, 1999).

One might assume that higher working memory leads to a higher ability to suppress unwanted thoughts. At this point, in regard to smoking specifically, thought suppression has been studied in more general terms. Pertaining to smokers, one such example of studies concerning suppression involves suppressing distracting stimuli (such as letters or symbols irrelevant to the task at hand) in one’s environment. (Park et al.,

2000) Little has been done to date, however, regarding smokers’ abilities to suppress unwanted and distracting thoughts. One point of interest, therefore, is whether it is easier for smokers and nonsmokers alike to suppress a neutral object, or a more meaningful specific area of smokers’ personal lives, such as a negative experience. Current speculation centers around nicotine possibly impairing an individual’s ability to suppress unwanted thoughts. This is often due to the decline in working memory found in many studies and due to the rebound effect, or an increase in unwanted thoughts due to the act of trying to inhibit these thoughts. By extension of Zwaan and Truitt’s study (2000), which found only the smokers had difficulty suppressing smoking related information, it is expected that smokers will have more difficulty in comparison with nonsmokers in suppressing unwanted thoughts.

Another question is whether the amount of time elapsed since smoking will influence smokers’ performance in thought suppression. Due to the possibility that smokers who abstain from smoking prior to the study may experience smoking urges that Does Smoking Affect Intrusive 5 impair their ability to concentrate, it is expected that these smokers will experience more suppression failures than those who smoked. Because the smokers who smoked before the study will likely not exhibit these smoking urges, it is expected that their concentration will be more focused, thus, having fewer suppression failures. Madden &

Zwaan (2001) attribute the decline in working memory to smoking urges; therefore, if one were not experiencing smoking urges, having just smoked, then one could assume that these smokers will have higher working memory and fewer suppression failures.

Toll (2001) has suggested that smokers experience more intrusive thoughts than nonsmokers as self reported on the White Bear Suppression Inventory (WBSI), a questionnaire measuring intrusive thoughts. One goal of this study is to replicate these findings. It is expected that smokers will report experiencing more intrusive thoughts than nonsmokers on the WBSI. By application of Toll’s study, one would also assume that individuals who report more intrusive thoughts on the WBSI will also have more difficulty in suppressing unwanted thoughts.

Finally, because the nicotine associated with smoking is thought to influence mood and cause anxiety, stress and possibly depression, negative affect will also be reviewed in this study. As indicated per Parrott (1999), smokers who quit become less stressed than previous levels, and smokers often feel that they need nicotine to feel

“normal.” Others have speculated that smoking could be a factor in developing depression in some cases. (Humphries, 2002) In this study, negative affect will be reviewed to determine if it is associated with smoking status and ability to inhibit unwanted thoughts. Does Smoking Affect Intrusive 6

METHODS

Materials.

Volunteers completed a modified version of the Fagerstrom scale (Heatherton,

1991) and returned the survey prior to the study. The survey contained questions in reference to one’s level of nicotine dependence. The Fagerstrom scale contained items such as “How many cigarettes do you smoke a day?” and “Do you find it difficult to refrain from smoking in places where it is forbidden, e.g., in church, at the library, in cinema, etc.?” All questions on the Fagerstrom scale were left intact. However, one question from the Minnesota Nicotine Withdrawal Questionnaire (Hughes & Hatsukami,

2003) was also added, “On a scale of 0 to 4 (with 0 being none, 1- slight, 2- mild, 3- moderate, and 4 being severe), how would you rate your desire or craving to smoke?”

Upon completion of the study, participants also completed two additional questionnaires.

The White Bear Suppression Inventory (WBSI; Wegner, 1994) was provided first, containing questions regarding intrusive, unwanted thoughts. Example questions include

“I have thoughts that I cannot stop.” and “I often do things to distract myself from my thoughts.” Participants responded how strongly they agreed or disagreed with the statements. A modified version of the Minnesota Nicotine Withdrawal Scale was provided as well. Because the questions measured negative affect and thinking about a negative experience prior to completing the survey could have a crossover effect, questions were added involving positive affect (e.g., happy, focused, patient following questions regarding depressed mood, difficulty concentrating, and impatient). This did not affect the validity of the questionnaire, as only the original questions regarding negative affect were measured. Does Smoking Affect Intrusive 7

Participants.

Participants involved in this study included 30 volunteers from an introductory psychology course at North Carolina State University in exchange for course credit for having participated in the study. The study consisted of one session only and was an individual study with only one participant per session. The participants were placed in one of three groups: nonsmokers (n = 10), smokers asked to refrain from smoking for one hour prior to the study (n = 10), and smokers asked to smoke 15 minutes prior to the study (n = 10). Smokers received a smoking questionnaire along with an informed consent form by visiting a website, which they completed and returned to the experimenter prior to the study. Smokers’ (n = 20) self reported dependency of nicotine was assessed using this questionnaire. Based on their level of dependency, they were placed into either the smoking group or the group that refrained. Individuals with similar scores on the Fagerstrom scale were paired together, with one person participating in the smoking group and the other in the refraining group. The average age of smokers was

18.7 years. Ages ranged from 19 to 21 years of age; in addition, 19 females and 11 males participated in the study.

Procedure.

Participants were provided with a website containing an informed consent form regarding the study and a modified copy of the Fagerstrom Nicotine Dependency Scale.

Participants completed and returned the Fagerstrom scale via email. The responses were reviewed, and the volunteers were placed into one of two groups (refraining for one hour preceding the study or smoking 15 minutes prior) based on their scores on the Fagerstrom Does Smoking Affect Intrusive 8 scale. Participants were then emailed and were asked to either refrain from smoking one hour prior to the study or to smoke 15 minutes prior to the appointment. Upon arrival for their appointed time, participants were greeted, and it was verified that they had indeed smoked or refrained as requested. If this was not the case, another time was rescheduled when the participant would be able to do so in order to maintain the integrity of the study.

All volunteers completed the study in a small plain room with a maximum capacity of two individuals, making it less likely that participants had any pre-existent cues in the room that would trigger a smoking urge that could cause more difficulty in attention.

After reviewing the informed consent, participants were asked to think of and describe in writing, any thoughts that come to mind when thinking of a coat rack. Participants wrote about these thoughts and associations for three minutes. Upon completion, the subjects were told that they could think about anything they wished for three minutes but were asked to try to suppress any thoughts related to the coat rack that they had previously wrote about. They were told if any thoughts related to the coat rack came to mind, they were to place a check on their page each time they thought about it. Next, participants were asked to think about and describe their thoughts and associations related to a negative or disappointing experience on a separate paper. Upon the completion of writing at the end of three minutes, the subjects were told that they were free to think about anything they wished but again, to try to suppress the negative experience. They were again asked to place a check on the page if any thoughts associated with the experience came to mind. At the completion of the thought suppression period, participants completed the White Bear Suppression Inventory, which measured the level of intrusive thoughts they generally experienced, and the Minnesota Withdrawal Scale, Does Smoking Affect Intrusive 9 measuring negative affect. At this point, participants were debriefed and thanked for their time.

RESULTS

Originally, 32 participants fully completed the study. Data was analyzed for 30 participants; data was discarded for two individuals from the original sample who did not appear to be following directions during the thought suppression period and occupied themselves in fashions not related to the study. Of the smoking groups, 13 females and 7 males participated; 6 females and 4 male nonsmokers completed the study. One individual had a substantial amount of suppression failures related to the negative experience. To account for this outlier, this score was entered as one value above the next highest score.

The difference in overall suppression failures between smokers and nonsmokers was analyzed using a 3 x 2 repeated measures ANOVA. The hypothesis that nonsmokers would have fewer suppression failures than smokers was not supported, F(2, 27) = .966, p =.393. No differences were found regarding the group the participant belonged to and ability to suppress unwanted thoughts, F(4,54) = 1.005, p = .413. Nonsmokers were slightly better at suppression of a neutral object while smokers were better at suppressing a negative experience. Though there was no significant difference, nonsmokers performed worse at suppressing unwanted thoughts on the negative experience compared to smokers. This is counter to what other researchers, such as Toll (2001), have suggested; one might assume if smokers report more intrusive thoughts, they may also have more difficulty suppressing unwanted thoughts. The means and standard deviations for each group are shown in Table 1. Does Smoking Affect Intrusive 10

Table 1. Neutral suppression Personal suppression WBSI MNWS Fagerstrom S- smoke 15 min prior 3.5(2.32) 4.8(3.74) 53.7(6.96) 13.3(5.50) 6.0(2.40) S- refrain 1 hour 4.5(2.84) 3.6(3.84) 55.9(13.40) 12.7(5.79) 6.7(1.95) Nonsmokers 3.3(1.95) 5.4(2.76) 50.5(7.28) 9.3(3.59) N/A

Note: standard deviations in parentheses

The hypothesis regarding the time elapsed after the last cigarette smoked and both smoking groups was measured using a 2 x 2 repeated measures ANOVA. No significant differences were found between the one hour abstention group and the group asked to smoke 15 minutes prior to the study. However, when accounting for nicotine dependence using the Fagerstrom scale as a covariate, smoking status was analyzed using another 2x2 repeated measures ANOVA with the Fagerstrom scale. When accounting for nicotine dependence, there was an interaction between the time elapsed since smoking and ability to suppress unwanted thoughts, F(1,17) = 5.866, p < .03. This interaction can be seen in

Figure 1. Smokers who were asked to smoke prior to the study initially performed worse on the neutral suppression but improved with the second task. Smokers who refrained for one hour initially performed better than those who smoked on the neutral stimuli, but their performance deteriorated with the second task. Does Smoking Affect Intrusive 11

Suppression failures as a function of smoking condition and suppression target s

r n u l a

i 5 e a F M

n Nondeprived d o e 3 i t s a Deprived

s 2 m e i r t p s 1 p E

u 0 S Neutral Negative Suppression Target

Figure 1.

While the application of Toll’s research to the number of suppression failures that smokers experienced in relation to nonsmokers was not replicated in this research

(smokers did not report more intrusive thoughts than nonsmokers), it does present other interesting findings regarding the WBSI scale. The questionnaire was positively related to suppression failures regarding a negative event at the .05 level (r = .400). This correlation indicates that individuals who self reported more intrusive thoughts on the

WBSI scale had more suppression failures in reference to a personal negative experience.

Of the three groups, nonsmokers reported experiencing the least amount of intrusive thoughts, μ = 50.5. Smokers who smoked 15 minutes prior to the study followed (μ = 53.7). Finally, smokers that refrained from smoking for one hour prior to the study reported the most intrusive thoughts (μ = 55.9). Though statistically insignificant, in terms of suppressing a negative experience, nonsmokers had a higher mean of suppression failures compared to smokers. Compared to Toll’s research, which found smokers having a higher score on the WBSI (M= 46.28) than ex-smokers Does Smoking Affect Intrusive 12

(M=40.36), the WBSI scores for this study were considerably higher; nonsmokers had the lowest score (M = 50.5), followed by smokers who smoked prior to the study (M =

53.70) and smokers refraining for one hour (M = 55.90).

Self reported intrusive thoughts on the WBSI scale were also related to negative affect / mood, as determined by the MNWS (r = .533). The relationship would indicate that individuals who report more difficulty in inhibiting unwanted thoughts have more negative affect, or vice versa.

MNWS scores were computed without one question pertaining to one’s desire or urge to smoke. Since the question was not applicable to the nonsmoking group and may have been influenced depending which smoking group one was assigned to, the question was not used.

In addition to intrusive thoughts, the MNWS scale had a significant relationship with the measure of suppression failures- both regarding a neutral stimulus (r = .524) and a personal event (r = .575)- and with the Fagerstrom Nicotine Dependence Scale (r = .

509). Individuals who expressed higher negative affect had more suppression failures and reported a higher level of nicotine dependence. One other interesting note is the correlation between the number of cigarettes smoked per day and number of suppression failures regarding a negative event (r = .541).

The number of suppression failures on the coatrack task was tested as a covariate to predict the ability to suppress thoughts regarding the negative event. No relationship was found. However, the Fagerstrom scale was also tested as a covariate to predict scores for suppression failures and found that the Fagerstrom scale did predict one’s ability to suppress unwanted thoughts: F (1,17) = 6.920, p < .02. Does Smoking Affect Intrusive 13

DISCUSSION

There were no differences in this study regarding one’s smoking status and ability to inhibit unwanted thoughts; this hypothesis was not supported in this study. However, when matched for nicotine dependence, the amount of time elapsed since smoking did have an effect on one’s suppression performance. Toll’s findings regarding smoking status and self reported intrusive thoughts were not replicated: smokers did not have a higher report of intrusive thoughts than nonsmokers. Negative affect was correlated with several measures, such as ability to suppress unwanted thoughts (both neutral and personal), self-reported nicotine dependence, and self-reported intrusive thoughts.

While this study presents interesting findings, there are some methodological weaknesses in the design that may affect validity. One such weakness was relying on self report to verify that individuals had followed the directions to either smoke prior to the study or to refrain, instead of relying on a more objective measure such as a CO meter.

Therefore, it was difficult to ascertain if the individual had, in fact, responded as requested outside of relying on self report. In the future, this study would be interesting replicated with such a measure to determine what differences may exist between the groups. There is some difficulty with ascertaining the effects of nicotine itself. At this point, it is usually studied through effects of smokers (abstaining or smoking for a specified time before the study). Therefore, several other factors may influence the results in these studies, such as the brand of cigarettes smoked, how many cigarettes were smoked prior to the study, the level of nicotine in each cigarette, and individual biological differences associated with how nicotine is processed. Does Smoking Affect Intrusive 14

Because smokers appeared to perform slightly better than nonsmokers at suppression, one may wonder why this might be the case. It could be, in part, due to having a larger sample size for the smoking groups (n = 20) versus the nonsmoking group (n = 10). Because each group only contained 10 participants, data was much more sensitive to any discrepancies in comparison between the three groups. It is difficult to determine with certainty that the difference in performance was due to one’s smoking status when other factors such as these are considered.

Despite efforts to counter negative affect as a result of writing about a negative experience by adding “positive” questions to the MNWS, it is possible that the negative emotions were more salient after expressing and suppressing a personal negative event prior to receiving this questionnaire. The very act of thinking about the experience may have made the individual feel that “in general”, they were higher in emotions of depression or anxiety than if they had not thought of the experience. Having more negative affect and anxiety, one may find it necessary to smoke. Here, it is also unknown if negative affect may be a result of smoking or vice versa. One study as described in a

Harvard Health Publication found that depressed individuals were more likely to start smoking; however, individuals who smoked were twice as likely to develop major depression (Humphries, 2002). This research would suggest that smoking can be a factor in developing depression.

In regard to suppression failures, chronic negative affect may hamper one’s ability to inhibit unwanted or irrelevant thoughts. Individuals high on neuroticism seem to have higher negative affect, in addition to a lower ability to suppress unwanted thoughts.

Though there is a high correlation between suppression failures and negative affect, it is Does Smoking Affect Intrusive 15 unknown whether it is unknown whether this is due to negative affect causing more suppression failures or the difficulty in inhibiting negative thoughts that lead to more negative affect.

This study found that nonsmokers were slightly better suppressing neutral stimuli

(ie, a coatrack) while smokers performed better at suppressing a negative experience.

This may be because nonsmokers have not had as much experience suppressing a negative experience, while smokers tend to use nicotine as an aide in inhibiting unwanted thoughts. This may cause causing novel stimuli more difficult for smokers to suppress.

Because nonsmokers reported less negative affect and fewer intrusive thoughts than smokers, suppressing novel stimuli may not be as difficult for this group compared to nonsmokers. Perhaps because fewer intrusive thoughts were reported, this group typically thought about the experiences less than smokers, making it more difficult for nonsmokers to suppress thoughts related to a negative event in their life when these thoughts did occur.

In addition, part of the reason that smokers who smoked prior to the study may have performed worse could be that they were preoccupied with thoughts of smoking.

As the study progressed, these participants may have accepted at that point in time, smoking was not an option. Whereas smokers who abstained from smoking initially performed better on suppression but deteriorated with the second task, may have been distracted by smoking urges and thoughts of smoking. This may have possibly caused a lessened ability to inhibit unwanted thoughts. Another question is if, knowing they could not smoke, abstaining smokers actually smoked more cigarettes before the hour prior to the study than general to compensate for not being able to smoke in the preceding hour. Does Smoking Affect Intrusive 16

Smoking is an area in which many psychological effects are still unknown or being investigated. This study has given more insight into some of the cognitive and emotional processes associated with smoking. This field is one in which more clarification is needed regarding the psychological and cognitive effects of smoking.

While research is ongoing, it does appear that smoking has harmful psychological and cognitive effects, in addition to the physical health effects that are more widely known. Does Smoking Affect Intrusive 17

APPENDICES

Table 2. Correlations- Overall Fagerstroma WBSIb MNWSb SuppCoatb Supp. Negb # daya Fagerstrom 1 .311 .509(*) .057 .552(*) .416 WBSI .311 1 .533(**) .302 .400(*) .158 MNWS .509(*) .533(**) 1 .524(**) .575(**) .309 SuppCoat .057 .302 .524(**) 1 .284 -.010 Supp. Neg .552(*) .400(*) .575(**) .284 1 .541(*) # day .416 .158 .309 -.010 .541(*) 1

* Correlation is significant at the 0.05 level (2-tailed). ** Correlation is significant at the 0.01 level (2-tailed). a: n = 20; b: n = 30

Table 3. Correlations- nonsmokersa WBSI MNWS SuppCoat Supp. Neg WBSI 1 .079 .255 .233 MNWS .079 1 .526 .716(*) SuppCoat .255 .526 1 .803(**) Supp. Neg .233 .716(*) .803(**) 1

* Correlation is significant at the 0.05 level (2-tailed). ** Correlation is significant at the 0.01 level (2-tailed). a: n = 10

Table 4. Correlations- Smokers smoking 15 min beforea Fagerstr WBSI MNWS SuppCoat Supp. Neg # day Fagerstr 1 .252 .757(*) .458 .693(*) .668(*) WBSI .252 1 .426 .677(*) .771(**) .533 MNWS .757(*) .426 1 .683(*) .744(*) .642(*) SuppCoat .458 .677(*) .683(*) 1 .564 .477 Supp. Neg .693(*) .771(**) .744(*) .564 1 .811(**) # day .668(*) .533 .642(*) .477 .811(**) 1 * Correlation is significant at the 0.05 level (2-tailed). ** Correlation is significant at the 0.01 level (2-tailed). a: n = 10 Does Smoking Affect Intrusive 18

Correlations- smokers refraining one houra Table 5 Fagerstr WBSI MNWS SuppCoat Supp. Neg # day Fagerstr 1 .373 .267 -.412 .488 .377 WBSI .373 1 .725(*) .110 .451 .056 MNWS .267 .725(*) 1 .416 .614 -.183 SuppCoat -.412 .110 .416 1 -.041 -.445 Supp. Neg .488 .451 .614 -.041 1 .109 # day .377 .056 -.183 -.445 .109 1 * Correlation is significant at the 0.05 level (2-tailed). a: n = 10 Does Smoking Affect Intrusive 19

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