Effects of ethanol and tobacco on auditory vigilance performance

Addictive Behaviors, Vol. 5, pp. 153-158, Printed in the USA. All rights reserved.

0306-4603/80/020153-06$02.00/O

1980

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19 80 Pergamon

Press Ltd

EFFECTS OF ETHANOL AND TOBACCO ON AUDITORY

VIGILANCE

PERFORMANCE

J.E. TONG, P.R. HENDERSON and BRENDA G.A. CHIPPERFIELD Department of Psychology, University of Guelph, Ontario

Abstract-Alcohol impaired vigilance prevented the time on task decrement.

performance

by human

subjects

and cigarette

smoking

Vigilance has been conceptualized as the maintenance of attention over long periods of time (Siddle, 1972). In the experimental situation the subject is faced with a task which demands that he retain a state of readiness to detect and respond to certain specified small changes occurring at random intervals in the external environment (Bakan, 1959; Mackworth, 1978). The typical finding in vigilance studies is a decline in performance over time, with the decline being termed the vigilance decrement. It has been proposed (Stroh, 1971) that the vigilance decrement is attributable to a parallel decline in the subject’s level of alertness or arousal across the task and there is some evidence that the decrement correlates with physiological change associated with arousal decline (Coles & Gale, 1971; Crider & Augenbraum, 1975; Gale er al., 1971; 1972; O’Hanlon, 1965). It has been suggested that alcohol effects the brain stem arousal systems (Goldberg, 1969; Kalant, 1970), hence one would expect that the drug would similarly influence vigilance performance. However, owing to the biphasic action of ethanol, the behavioral effects are likely to be paradoxical with a small dose facilitating performance and a large does enhancing the vigilance decrement and there is some evidence that this is so (Colquhoun, 1976). Other studies have claimed that vigilance performance is unimpaired by alcohol (Dotter et al., 1966; Moscowitz & Depry, 1968; Talland, 1966). It is questionable if these latter studies satisfy the time factor requirement of the classic vigilance situation as the tasks were less than thirty minutes duration. Furthermore, there was no control over tobacco usage by the subjects and there is evidence that tobacco smoking exerts a profound effect on tasks involving sustained attention (Frankenhaeuser et al., 197 1) and prevents the vigilance decrement from occurring (Tarriere & Hartemann, 1964; Tong et al., 1977). We have reported elsewhere that the stimulant effect of nicotine, which also acts upon the arousal systems, can prevent the deleterious effect of ethanol from being apparent with various cognitive tasks (Leigh et al., 1977; Lyon et al., 1975; Tong et al, 1974). The following experiment tests the hypotheses that ethanol alone at a blood alcohol concentration of 0.06% will impair vigilance performance and that the simultaneous smoking of cigarettes will reduce the ethanol impairment.

METHOD

Subjects

The subjects were 32 male smokers ranging in age from 18 to 30 years and in attendance at the University of Guelph during the 1978 summer session. The subjects were selected on a volunteer basis the only requirements being that they had moderate alcohol habits and consumed a minimum of 12 cigarettes daily. Subjects were paid for their participation on completion of the second session.

153

154

J.E. TONG,

P.R. HENDERSON

and BRENDA

G.A. CHIPPERFIELD

Apparatus The apparatus was virtually identical to that employed in an earlier tobacco study (Tong ef al., 1977). The auditory vigilance task consisted of a 72 minute monaural tape recording of a male voice reading a continuous sequence of digits at a constant rate of one digit per second divided into six 12 minute blocks. A signal was defined as three consecutive (but not necessarily sequential) odd but unequal digits. Signals were prepared from random digits (constrained in not having signal sequences). Across the six blocks there were a total of 72 signals distributed evenly 12 per block. Assignment of signal position within a block was random with no less than 10 and no more than 110 seconds elapsing between signals. To counteract any block order effect or recognition of blocks from day to day, two taped versions of the task were employed. In one the blocks were presented in sequence, 1,2, 3,4, 5, 6, while in the other the block order was 4, 5, 6, 1, 2, 3. Order of tape presentation was counterbalanced across subjects. The first block of each tape was designated as the Baseline block and the remaining five comprised the test session. All five test blocks were separated by a two minute silent interval. Earlier (Tong et al., 1977) we reported that such pauses were necessary as subjects frequently found a continuous task too demanding and terminated testing. In addition, such interblock intervals allowed the inclusion of nicotine booster sessions. In an attempt to control nicotine intake during these sessions, all two minute interblock intervals were divided into four subperiods (25, 60, 25, and 10 seconds) the beginning of which were signalled by one, two, three, or four 1000 Hz tones respectively. Booster sessions were thus temporarily regulated through the onset of a signal specific to each step in the smoking procedure. The experiment was conducted in a diffusely lit 1.98 x 2.42 m room partitioned into three identical .76 x 1.37 m booths constructed to provide a neutral environment with minimal visual or auditory distraction. Each booth contained a desk. On the wall directly in front of the subject was posted a sheet summarizing the interblock smoking procedure. Digits were presented through SONY DR-7 headphones from one or two SONY TC-106 monaural half-track tape recorders located in an adjacent control room. BAC was determined by a Stephenson Model 900-A Breathalyzer which was also used during Placebo conditions. On the subject’s desk was squared recording paper on which he was instructed to make a check to represent every digit heard and to write the last digit of the signal sequence when that occurred. Design Subjects were randomly assigned to one of two treatment groups: a Tobacco group (T) in which smoking was scheduled and a No Tobacco group (NT) in which smoking was not scheduled during the two experimental sessions. All subjects were tobacco deprived for a 12 hour period previous to testing. Within each treatment group, all subjects were tested on the task (6 blocks) twice, once under an alcohol condition and once under a placebo condition. Thus the basic design was that of a one between (Tobacco, No Tobacco) and two within (Alcohol, Placebo x 5 Blocks) mixed design. The treatment conditions can be summarized as follows: A. (1) No Tobacco, No Alcohol (2) No Tobacco, Alcohol (.06% BAC) B. (1) Tobacco, No Alcohol (2) Tobacco, Alcohol (.06 BAC) Subject Treatment conditions, alcohol or placebo, as well as the vigilance tape used in each session were counterbalanced across subjects. Procedure Orientation Session. Previous to testing, all subjects were required to attend an individual orientation session. At this time body weight, the extent of the participant’s alcohol and tobacco habits, as well as his current daily cigarette consumption were recorded. Requirements regarding abstention from all forms of tobacco, coffee, tea, and cola drinks for the 12 hour period previous to testing were carefully reviewed during this session.

Ethanol

and tobacco

effects

on auditory

vigilance

155

Task instructions were presented in detail verbally by the experimenter, and then the participant was seated in the testing booth and listened to a recorded summary. A 12 minute practice trial followed, i.e., a full block. Subjects were informed of their performance and any questions concerning the task answered. S’s not achieving a 66% Hit Rate were excluded from further testing. Alcohol and Tobacco Administration. In appropriate conditions, alcohol was given in the form of 35% ethyl alcohol (Liquor Control Board of Ontario) at a dosage of 1.875 ml/kg body weight calculated to produce a BAC of .06%. The vehicle, 40% unsweetened orange juice prepared from frozen concentrate, consisted of 1.5 times the volume of the alcohol dosage. The placebo beverage was comprised of orange juice equal in volume to the alcohol plus vehicle employed in the alcohol condition. To disguise the taste, four ml of alcohol was floated on the surface. Beverages were divided equally into two identical glasses and served chilled. Tobacco conditions involved the use of standard 70 mm filter tip cigarettes having a nicotine and “tar” content of 1.3 and 18 mg respectively. To maintain uniform nicotine intake the length of each cigarette was partitioned into 5 mm segments. Tobacco-designated participants were instructed to inhale on the cigarette such that each puff consumed a 5 mm segment. Each inhalation was held for 5 seconds and a 60 second inter-puff interval was maintained. Smoking within interblock intervals was regulated by the tones recorded on the vigilance tape. A single tone on the conclusion of a block signalled the subject to light and inhale from one of the two cigarettes provided. Inhalations were held to a count of five. The second inhalation was signalled by a double tone 25 seconds after the first, the third inhalation 60 seconds following the second by a triple tone after which the cigarette was extinguished. Finally, a four tone series instructed the subject to prepare for the next block of the task. To control for the distraction and novelty involved in the inter-block smoking procedures, No Tobacco subjects were instructed to perform every step of the smoking process. To guarantee the preservation of the No Tobacco condition, however, this group was provided with a booklet of intact but useless matches. Thus each maneuver for this group was performed with an unlighted cigarette. Testing. All test sessions were conducted between 900 and 1200 hours. Session times for each subject were held constant. Where possible testing was carried out in groups of threes but because Tobacco and No Tobacco subjects could not be tested together, the intersession period was somewhat varied. Upon arrival, subjects were questioned as to whether they had fulfilled the abstention requirements. Those who failed to do so had testing rescheduled and were dismissed. Participants were asked to surrender their watches and cigarettes. Testing was initiated by the twelve minute Baseline block of the vigilance task. Subjects were then taken to individual rooms and presented with the beverages and, where appropriate, two cigarettes. It was required that the beverage be consumed in the first ten minutes of a 25 minute drinking absorption period. The Tobacco group was told to smoke the cigarettes in the prescribed manner, lighting the first immediately and the second at minute 17 as indicated by a stop clock. Upon conclusion of the 25 minute period, the subjects were sent individually to the washroom. BAC assessment was then made, following which a review of the steps in the interblock smoking procedure was given. The five 12 minute test blocks of the vigilance task were then presented. With task completion all subjects were administered the post-test Breathalyzer. The entire test session lasted approximately 120 to 150 minutes.

RESULTS

Breathalyzer readings indicated mean BAC’s of 0.058% for the pretest assessment and 0.057% for the post-test assessment. The vigilance data were analyzed in terms of the percent number of correct signal sequences recorded and also the percent number of errors, i.e., checks indicating detections when no signal sequence occurred. Two sets of scores were used, these being the actual percent of detections and errors in the five test blocks and the difference

156

J.E. TONG,

Table 1. Means and standard test block.

P.R. HENDERSON deviations

and BRENDA

G.A.

of correct

detections

in the number

CHIPPERFIELD for each treatment

No tobacco

1 2 3 4 5

9.875 9.437 9.687 8.250 9.000 8.750

Alcohol IVJ SD

1.310 2.096 2.024 2.595 2.160 2.720

*Base refers to pre-treatment

Table 2. Means and standard condition and test block.

10.000 8.000 9.750 7.563 7.875 8.312

No alcohol M SD

1.713 3.011 2.016 3.119 2.849 2.869

8.812 9.187 9.125 8.687 8.187 9.062

1.377 2.136 2.363 2.65 1 2.482 1.843

deviations

for the number

of incorrect

detections

(errors)

No tobacco

1 2 3 4 5

1.562 0.812 1.062 0.812 0.875 0.937

M

1.093 1.265 1.549 1.857 1.413 1.366

1.375 0.687 0.750 1.323 0.750 1.375

-0.437 -0.187 -1.625 -0.87 5 -1.125

deviations

1.590 1.797 2.125 2.094 2.277

deviations

for the difference

scores for correct

1 2 3 4 5

-0.750 -0.500 -0.750 -0.687 -0.625

SD

1.250 0.625 1.375 1.562 0.937 0.750

1.666 0.516 1.813 2.129 0.995 1.667

detections. Tobacco

Alcohol M

SD

-2.000 -0.250 -2.437 -2.125 -1.687

2.708 1.527 2.606 2.334 2.414 of detections

for the difference

1.483 1.932 1.000 1.662 1.306

Alcohol

No alcohol M SD 0.375 0.312 -0.125 -0.625 0.250

2.029 1.991 2.334 2.029 2.145

M

SD

-1.562 -0.875 -1.125 -0.500 -1.187

2.365 2.061 3.181 2.160 2.428

in the test block minus the number

scores for incorrect

detections

No tobacco No alcohol M SD Block Block Block Block Block

Alcohol M

score.

Note:The difference score is the number the pre-treatment block.

Table 4. Means and standard

1.612 2.676 2.187 2.604 2.175 2.144

for each treatment

1.784 0.873 1.000 0.946 0.774 1.586

No tobacco

1 2 3 4 5

9.250 7.687 8.375 8.125 8.750 8.062

No alcohol M SD

SD

1.437 1.000 1.500 1.875 1.437 1.000

No alcohol M SD Block Block Block Block Block

SD

Tobacco Alcohol

1.365 0.911 1.236 0.911 0.957 1.843

*Base refers to pre-treatment

Table 3. Means and standard

Alcohol M

score

No alcohol M SD Base* Block Block Block Block Block

and

Tobacco

No alcohol M SD Base* Block Block Block Block Block

condition

of detections

in

(errors).

Tobacco Alcohol M

SD

-0.437 0.062 0.437 0.000 -0.437

1.548 2.048 1.711 1.633 1.672

Note: The difference score is the number of incorrect incorrect detections in the pre-treatment block.

No alcohol M SD -0.687 -0.625 -0.062 -0.625 0.000 detections

2.120 1.927 1.806 1.746 1.129

in the text block

Alcohol M

SD

-0.625 0.125 0.312 -0.312 -0.500

1.088 1.310

1.448 0.873 1.033

minus the number

of

Ethanol and tobacco effects on auditory vigilance

157

between the test block scores and the pretreatment baseline score for that test session. All four scores were subjected to a mixed design-2 (tobacco groups) X 2 (alcohol treatments) X 5 (test blocks) analysis of variance. Signals Detected The ANOVA’s indicated a significant main effect for alcohol on actual correct detections (F = 12.08, df l/30, P < .OOl) and on the difference scores (F = 7.90, df l/30, P < .008). Similarly, a main effect for the blocks factor was present for both actual correct detections (F = 4.29, df 4/120, P < .002) and the difference scores (F = 4.28, df 4/120, P < .002).Tables 1,2,3 and 4 give the means and standard deviations for all scores from which it will be seen that alcohol reduced the correct detections, both absolute and difference scores, and detections decreased with time on task. There was no main effect for the tobacco factor but the analysis was marginally significant for the tobacco X blocks interaction indicating that the tobacco treatment prevented the vigilance decline over time: (absolute scores: F = 2.01, df 4/120, P < .09; difference scores F = 2.04, df 4/120, P < .09). In order to examine maximum drug effects the difference scores for the first three blocks were similarly analyzed. Again, significant main effects were present for alcohol (F = 6.73, df l/30, P < .Ol) and blocks (F = 3.49, df 4/120, P < .009) but not for tobacco. In this analysis, the tobacco X blocks interaction was clearly significant (F = 3.05, df 2/60, P < .05). No other significant interaction was present. Errors The ANOVA of the absolute scores barely brought out a marginally significant main effect for alcohol (F = 3.65, df l/30, P < .06) and a significant effect for blocks (F = 3.30, df 4/120, P < .Ol). There was no tobacco effect and no significant interaction. Analysis of the difference scores brought out a blocks effect only (F = 3.15, df 4/120, P < .009). Using the difference scores for the first 3 blocks, the ethanol effect approached significance (F = 3.66, df l/30, P < .06) and again the blocks effect was more pronounced (F = 6.07, df 2/60, P < .004). Alcohol treatment very slightly increased the number of errors which also increased with time on task.

DISCUSSION The task clearly meets the criterion of a vigilance situation in that there was a marked performance decrement associated with time on task with the decrement being present after about 30 minutes. Alcohol also produced a performance decrement but did not greatly increase the number of errors suggesting that the drug induced decrement was the result of a cognitive impairment and not the result of increased risk taking. The absence of an interaction between alcohol and time on task is of interest in the light of the reported effects of these two factors on the heart rate increase associated with performance on this task (Tong ef aZ., 1979). With other subjects we found a highly significant interaction between time on task, alcohol, and tobacco showing as an increase in the heart rate of a mean magnitude of 22.3 b.p.m. over base under the 2 drug treatments by block 5. So far as alcohol was concerned this large heart rate increase was interpreted as being partly due to the stress of maintaining performance under impaired conditions, an argument somewhat supported by the current analyses of the error scores. The tobacco and time on task interaction indicating that tobacco prevents the normal vigilance decrement over time is in line with previous results (Tong et al., 1977) and possibly the most important feature of this finding is to indicate the crucial nature of tobacco smoking as a confounding variable in this area of research. Although a tobacco X alcohol interaction was not present in the results a comparison of the total difference scores for signals htected for all 5 blocks (Table 3) shows that the order of performance from best to worst for the four treatment conditions supports previous suggestions that tobacco smoking can prevent the deleterious effect of alcohol on cognitive performance. As expected, best performance was associated with tobacco but no alcohol (total mean difference from base 0.187 detections), followed by the no tobacco-noalcohol condition (-4.249), then tobacco plus alcohol (-5.249) with the worst performance being in the no tobacco plus alcohol condition (-8.499).

158 Acknowledgment the Non-Medical Tong.

J.E. TONG,

P.R. HENDERSON

-This study was assisted use of Drugs Directorate,

and BRENDA

GA.

CHIPPERFIELD

under the program of Research on Drug Abuse administered by Ministry of Health and Welfare, Canada by a grant to Dr. J.E.

REFERENCES Bakan, P. Extraversion-introversion and improvement in an auditory vigilance task. British Journal of Psychology, 1959, 50, 325-332. Coles, M. & Gale, A. Physiological reactivity as a predictor of performance in a vigilance task. Ps_+jchophysiology, 1971, 8,594-599. Colquhoun, W.P. Estimation of critical BAL in relation to tasks of sustained attention. In Adverse Effects of Environmental Chemicals and Psychotropic Drugs, Vol. 2, Amsterdam: Elsevlen, 1976. Crider, A. & Augenbraum, C.B. Auditory vigilance correlates of electrodermal response habituation