Gilboy's prognosis gives little hope. But his continuing fight in the Louisiana courts against the American Tobacco Co. provided a glimmer of hope last June in an Ohio State University research laboratory where psychologist Timothy Brock and associate Laura Brannon were conducting experiments. To test their impact, they modified the "vividness" of health warnings on actual print ads for cigarettes. They found that today's standard text warning labels had practically no effect on the consumer attitudes of 102 subjects. Neither did enlarging and centering the warning in the ad.