The Role of Temporal Proximity in Fear Learning and Intrusive Memories during a Trauma Film Conditioning Paradigm

Intrusive memories are a central feature of posttraumatic stress disorder (PTSD) and are thought to emerge through associative learning processes during trauma. Cognitive models propose that conditioned stimuli (CSs) occurring in close temporal proximity to a traumatic event should form particularly strong associations with the unconditioned stimulus (US). Recent shock-based conditioning research suggests that a CS presented simultaneously with the US (CSX) may reduce return of fear when extinguished during extinction. The present study sought to replicate and extend these findings using a trauma film conditioning paradigm and to examine whether CSX extinction reduces intrusive memory frequency. Ninety-eight healthy participants completed a multi-phase conditioning task in which angry facial CSs were paired with aversive or neutral film clips. During acquisition, a CS+ preceded aversive clips, a CS− preceded neutral clips, and a CSX was co-presented with aversive clip onset. Participants were allocated to CS+ or CSX extinction, followed by renewal and reacquisition phases. Skin conductance reactivity and US expectancy were recorded throughout, and intrusive memories were assessed during the laboratory session and over four subsequent days using diary methods. Contrary to hypotheses, CSX extinction did not reduce return of fear or intrusive memory frequency relative to CS+ extinction. Differential skin conductance responding was not reliably observed, limiting evidence of successful conditioning. These findings suggest that the effects of CS–US temporal proximity observed in shock-based paradigms may not readily generalise to trauma film USs, highlighting important boundary conditions for experimental models of fear and intrusive memory development.