However , sustained attention , as measured by the Rapid Visual Information Processing ( RVP ) CANTAB test , showed a statistically significant interaction of fed versus fasting and post-dose time of testing ( F -LSB- @,@ -RSB- = @ , P = @ ) , suggesting that @mg oxymorphone ER after a high-fat meal versus fasting mitigates the learning effect in this particular cognition domain from @ hour to @ hours post-dose .