Characterising the declarative-procedural transformation in instruction-based learning.

Many accounts of instruction-based learning assume that initial declarative representations are transformed into executable procedural ones, so as to enable instruction implementation. We tested the hypothesis that declarative-procedural transformation should be bound to a specific response modality and not transferable across different modalities. In Experiment 1, novel stimulus-response instructions had to be implemented either verbally or manually either once or three times. Modality-specific procedural encoding was probed via a subsequent implicit priming test. This involved the same stimuli but required a response that could be either compatible or incompatible with the originally instructed response using either the same or a different response modality. We found that procedural encoding was modality-specific as indicated by a stronger repetition-dependent increase of the compatibility effect when response modality was unchanged. Explicit test performance, serving as a marker of declarative encoding, was independent of modality transition and it was uncorrelated with implicit test performance. Unexpectedly, the implicit priming test also revealed a small yet significant transfer to the response modality that was previously overtly implemented, likely reflecting covert response "simulation". To examine if covertly simulated responding occurs even when instruction implementation is omitted altogether, we conducted Experiment 2. Subjects merely viewed novel stimulus-response instructions prior to testing. Again, we found evidence for procedural encoding of the non-implemented instructions. Moreover, a direct comparison of both experiments revealed higher test scores (both implicit and explicit) for previously non-implemented instructions than for previously implemented instructions. This calls for theoretical reconciliation with diverging previous study results.