Table 12.

Summary of Parameter Estimates for Younger and Older Adults with Ratio of Differences Across Age

Parameter of interest	Younger adult estimate (Card, Moran, & Newell, 1983)	Older adult estimate (Jastrzembski, 2006)	Ratio of old to young
Duration of saccadic eye movements	230 ms (70–700)	267 ms (248–286)	1.16:1
Decay half-life of visual image store	200 ms (90–1000)	159 ms (135–183)	0.8:1
Cycle time of the perceptual processor	100 ms (50–200)	178 ms (161–195)	1.78:1
Cycle time of the motor processor	70 ms (30–100)	146 ms (128–164)	2.1:1
Power law of practice constant	0.4 (0.2–0.6)	0.49 (0.39–0.59)	1.2:1
Fitts’ law slope constant	100 ms/bit (70–120)	175 ms/bit (163–199)	1.75:1
Effective capacity of working memory	7 items (5–9)	5.4 items (4.9–5.9)	0.77:1
Pure capacity of working memory	2.5 items (2.0–4.1)	2.3 items (1.86–2.52)	0.92:1
Cycle time of cognitive processor	70 ms (25–170)	118 ms (102–134)	1.69:1