Hours Played and What Remained: Residual Urge at 30 Days in 743 Crew Members Exposed to the Ktarian Game Aboard USS Enterprise (NCC-1701-D), 2368

1. Introduction

In 2368 a Ktarian visitor gave a game to an officer on leave, who brought it aboard USS Enterprise. The player wore a headset that projected a pattern of light into the eyes, and the game rewarded the player with a sensation that the ship's medical staff identified as stimulation of the brain's pleasure centres. Play spread from officer to officer, the crew came to prefer the game to their duties, and the ship's command was compromised until the game's effect was interrupted. An android officer was not affected, and a young Academy student and an ensign, both of whom had recognised the danger, took part in ending it (Starfleet Incident Records, 2368).

The episode ended, but the crew members who had played did not all leave it unchanged. Some described a continuing wish to play in the weeks that followed, and the sickbay wanted to know how common this was and what it depended on. Reward stimulation of the kind the game produced is known to leave a residue in some people and not in others, and work on similar stimulation suggests that the amount of exposure matters (Fenwick-Aldous, 2370). We do not have a controlled study of it. We have the records of a ship that exposed most of its crew to the same stimulus and then followed them.

Our question is whether residual urge at 30 days depends on the cumulative hours a person played. We write in 2372, from the sickbay's follow-up records.

2. Methods

Sickbay follow-up records for the Enterprise crew who played the game are held in the Starfleet Medical Records Archive (Starfleet Medical Records Archive, 2368). About a thousand people were aboard. The sickbay identified 795 as having played at least once, from the usage logs of the game units and from crew statements, and it reconstructed a window of 19 days between the first play aboard and the withdrawal of the game. The sickbay offered each of them a structured interview 30 days after the game's use was stopped. We excluded 52 who did not complete it, because they had been transferred off the ship or were otherwise not available, and we analysed the remaining 743. The 52 were spread across the exposure categories: 22 in the lightest (7.6% of that category's crew), 17 in the middle (5.5%) and 13 in the heaviest (6.6%).

The exposure was cumulative hours of play within that window, reconstructed by the sickbay from the same sources. We divided it into three categories, under 10 hours, 10 to 39 hours, and 40 hours or more. The cut points were fixed before the outcome was tabulated. The outcome was residual urge, defined as an endorsement of at least one of three questions in the sickbay's structured interview about a wish to play, a search for the game or a difficulty in putting the thought aside (Delvaux-Ferro, 2367). Two clinicians independently rated the interview responses of 60 crew members, and their agreement was κ = 0.84 (Cohen's kappa).

We report the proportion with residual urge in each category with Wilson intervals, and the difference between the heaviest and lightest categories with a Wald interval. We tested the trend across the ordered categories with the Cochran–Armitage test (Ombeni-Rask, 2371) and compared the categories with an overall chi-square test. Because hours played may differ by duty, we grouped the crew into three sets of departments, command and operations, sciences and medical, and engineering and security, and combined the odds ratios across them with the Mantel–Haenszel method (Tolliver-Braga, 2370). All tests were two-sided at .05.

3. Results

Of the 743 crew members analysed, 268 (36.1%) were in the lightest exposure category, 291 (39.2%) in the middle category and 184 (24.8%) in the heaviest. Residual urge at 30 days was reported by 158 (21.3%; 95% CI 18.5 to 24.4).

The proportion rose with each step in exposure (Table 1). It was 7.8% (21 of 268; 95% CI 5.2 to 11.7) in the lightest category, 19.9% (58 of 291; 15.7 to 24.9) in the middle category and 42.9% (79 of 184; 36.0 to 50.2) in the heaviest. The chi-square test with 2 degrees of freedom gave 80.8 (p < .001), and the Cochran–Armitage trend test gave z = 8.8 (p < .001). The heaviest category exceeded the lightest by 35.1 percentage points (95% CI 27.3 to 42.9).

In crude terms the odds of residual urge in the middle category were 2.9 times those in the lightest (95% CI 1.7 to 5.0), and in the heaviest category they were 8.8 times as great (95% CI 5.2 to 15.1). The heaviest category had 3.0 times the odds of the middle category (95% CI 2.0 to 4.6).

The pattern held in each set of departments (Table 2). The odds ratios for the heaviest category against the lightest were 13.5 in command and operations, 6.2 in sciences and medical and 9.1 in engineering and security, and the strata are too small to test the differences between them formally. Among command and operations crew, residual urge was 5.6%, 17.7% and 44.7% across the three categories. It was 9.8%, 19.5% and 40.4% among sciences and medical crew, and 7.6%, 22.1% and 42.9% among engineering and security crew. The Mantel–Haenszel odds ratio was 3.0 for the middle category against the lightest (95% CI 1.8 to 5.1) and 9.0 for the heaviest (95% CI 5.2 to 15.6), close to the crude values.

4. Discussion

Residual urge was common, and it was closely tied to hours played. About one in five of the crew who played reported a lingering urge at 30 days, and the proportion was about one in 13 among those who played least and about two in five among those who played most. The gradient was steep and regular, and it appeared in each set of departments, so a difference in duty is unlikely to explain it.

The finding fits what is known of reward stimulation. A stimulus that acts directly on the pleasure centres can leave a person with a lasting wish to seek it out, and the wish grows with repeated exposure (Kasprzak-Nyberg, 2369). Our records add a count from one ship's crew. They cannot show why the wish persisted in some and not in others. Whether the effect depends on the individual's own neurophysiology is a separate question, and our data cannot address it.

A number of this kind has a use. Follow-up after a stimulus of this kind need not be the same for everyone. Crew members who played for 40 hours or more were about twice as likely as those who played for 10 to 39 hours to report a residual urge (risk ratio 2.2). We do not offer a threshold, because the categories are broad and their cut points were fixed in advance and not tuned to the data.

5. Limitations

Hours played were not assigned. A person who played for a long time may have done so because the game was already rewarding to them, and the same susceptibility could explain both the hours and the residual urge. The association is therefore not a measure of the effect of hours alone. The outcome was reported in an interview, and although two clinicians agreed closely on the rating, the report itself was self-reported. Fifty-two people were lost to follow-up, and their outcomes are unknown. We did not compute a bound on the effect of the losses, and the proportions could be biased if the losses were related to urge. The analysis also treats crew members as independent, although they were exposed through networks of colleagues and departments, so the intervals are probably too narrow. The usage logs and statements recorded hours of play and not the intensity of the experience, and the reconstruction of hours is the sickbay's own. We did not have information on the time each person had spent in the game before the logs began, and the crew members who were not identified as players may include some who played out of sight of the logs. The study describes one ship and one episode. Its results cannot be extended to other stimuli or to crews that were not exposed in this way, and the categories used here are broad.