Directed forgetting of stimulus-response associations

Humans can intentionally forget previously-learned information (directed forgetting, DF). Whereas many studies have demonstrated DF for lists of items (e.g., words), where memory for to-be-remembered (TBR) items is typically better than for to-be-forgotten (TBF) ones, the role of intentional forgetting in action control is less clear. Here, we investigated whether the instruction to remember or forget a stimulus affected the formation and/or retrieval of corresponding stimulus-response (S-R) associations. To do so, we combined the DF item-method with item-specific priming: By categorizing stimuli (Exp. 1-3: images, Exp. 4: words) in a prime phase, participants formed S-R associations. Directly after participants' responses, a memory cue indicated whether to remember or forget the stimulus for a later memory test. In the following probe phase, participants responded to the same stimuli, but the required response item-specifically repeated or switched. Typically, probe responses are faster for item-specific response repetitions rather than switches (S-R effect). In four experiments, these S-R effects did not differ between TBR and TBF stimuli. This was the case when S-R associations already existed before the memory instruction was given (Exp. 1), when stimulus, response, and memory cue were paired multiple times (Exp. 2), when learning new S-R associations (Exp. 3), and when using a different categorization task and word stimuli (Exp. 4). Thus, up- or downregulating the memory strength of a stimulus representation by the intent to remember or forget it does not inevitably affect the corresponding S-R association. This suggests that top-down memory control selectively operates on certain but not all representations associated with a learning episode (event file)