“…(c) Retention performance may be positively correlated with the amount of cognitive effort allocated to the criterion task. This assumption has received support in several studies (e.g., Ellis et al, 1984;Jacoby, 1978;McFarland, Frey, & Rhodes, 1980;O'Brien & Myers, 1985;Swanson, 1984;Tyler, Hertel, McCallum, & Ellis, 1979). At present, this assumption implies only a correlation between effort and memory and does not assume a causal relationship; moreover, the mechanisms underlying this relationship are yet to be understood.…”