No Memory Needed? Perceptual Matching Accounts for a Large Part of the Working Memory–Intelligence Link

Working memory capacity (WMC) and fluid intelligence (Gf) are strongly correlated, usually attributed to shared demands on WM maintenance. We test this account against an alternative: shared representational quality. We included an experimentally controlled simplification of visual WM tasks – a perceptual matching task without maintenance demands – alongside WMC and Gf measures. Study 1 (N = 346; younger and older adults) used color and orientation stimuli; Study 2 (N = 267; younger adults) added luminance matching and a broader WMC battery. Matching accuracy strongly predicted Gf and accounted for a large share of the WMC–Gf covariance. WM maintenance accounted for unique Gf variance over and above matching in all groups. These findings are consistent with a shared signal-to-noise ratio affecting perceptual discrimination, WMC, and Gf. They question the view that the WMC–Gf relationship reflects only demands on WM maintenance, while confirming a specific role of maintenance for Gf.