A single dimension of memory strength underlies semantic and phonological false memories

False memory can be induced from experiencing semantically or perceptually similar events, as demonstrated in the Deese-Roediger-McDermott (DRM) paradigm. Although semantic and phonological DRM tasks yield parallel false recognition patterns for non-presented critical lures (CLs), prior work argued they reflect distinct processes, based partly on findings that semantic CLs elicit more false “Remember”(R) judgments, whereas phonological CLs elicit more false “Know”(K) judgments. The current study directly evaluated this claim by testing both semantic and phonological DRM tasks with old-new recognition and RK ratings. We replicated the RK dissociation, yet both parametric and non-parametric analyses indicated a single underlying dimension. First, a signal detection theory model provided a near-perfect fit to the data where R judgments merely reflect a higher response criterion than K. Moreover, a state-trace analysis uncovered a monotonic relationship between semantic and phonological overall and R false alarms. These findings challenge dual-process interpretations of false memory.