Abstract
Stress can modulate the balance between explicit (hippocampal‐dependent) and implicit (striatal‐dependent) memory systems, but the impact of post-learning stress, particularly on implicit memory, remains largely unexplored. We examined whether acute stress administered after incidental sequence learning alters subsequent retrieval of implicit and explicit knowledge. Sixty‑six university students first completed 12 blocks of a serial reaction‑time task (SRTT) embedding a second‑order conditional sequence. Immediately afterward, they underwent either the socially evaluated cold‑pressor test (SECPT; 3 °C, 3 min; n = 35) or a warm‑water control (36 °C; n = 31). During the test phase, participants typed short “old” (trained) and “new” (untrained) subsequences and then judged each fragment as old/new with a 6‑point confidence rating. A 2 (stress) × 2 (sequence type) mixed ANOVA on reaction times (RTs) showed faster responses to old than new fragments (p = .048, η²ₚ = .06), but the stress main effect and the interaction were not significant, indicating a comparable old–new advantage in both groups. Recognition scores likewise revealed a main effect of sequence type (p < .001, η²ₚ = .20), with no stress effect or interaction, confirming that explicit discrimination was equally strong in stressed and control participants. Acute stress applied immediately after learning
neither impaired nor enhanced retrieval of procedural nor declarative knowledge. Implicit and explicit measures evolved similarly, consistent with a parallel-or at least non‑competitive- relationship between memory systems under these timing conditions. Our findings establish a clear baseline for acute stress administered immediately after learning, against which future studies can compare stress applied at other stages: before encoding, during consolidation, or after variable delays preceding retrieval.