Figure 3.

Illustration of two possible ways in which sleep deprivation (SD) can affect speed and accuracy variables. Two sources of change may potentially occur following a period of total SD: a downward shift of the performance curve and a movement along the curve. In the case where δ₁ = δ₂ (i.e., there is a move to point S₁), no bias toward speed or accuracy occurs following SD. A movement along the curve (i.e., to S₂), however, would represent not just an overall decrement in performance but also a bias toward more accurate responding.