Implicit memory for auditorily presented threatening stimuli: A process-dissociation approach

The investigation of unconscious cognition involves especially problems wit h the methodology of measuring implicit and explicit proportions of differe nt: task performances. In this study the process dissociation procedure of Jacoby and its modification within the multinomial modelling framework for an indirect word-nonword-discrimination task is applied to a sample of 45 h ealthy students. The paradigm includes acoustically presented stimuli. Duri ng a learning phase, subjects listened to a series of neutral and threateni ng words. Performance was tested by letting subjects decide whether a prese nted stimulus (masked with white noise at signal-noise ratio of -17dB or un masked) had been a word or a nonword. Within this paradigm, implicit cognit ion occurs when (a) a word is more probably correctly recognized as "word" after presentation during the learning phase (typical priming effect) or wh en (b) a nonword derived from a word is more probably falsely recognized as "word" after its corresponding word had been presented during the learning phase (effect of implicit cognition given perceptual fluency). Frequencies for hits and false alarms were analyzed within the multinomial model which allows estimating parameters for the correct discrimination of words (c), the response bias (kr), the classical priming effect (u1), and the paramete r for the priming effect of "old" nonwords (u2). Under masked stimuli the m ultinomial model showed implicit cognition, an effect not equally found for neutral and threatening words. Threatening words exhibited a significantly higher portion of implicit cognition than neutral ones. Given the statisti cal complexity of multinomial models, the application of this method was ex plained in detail.