Orienting, Habituation, and Short-Term Memory

Two experiments investigated the relationship between orienting activity and proactive inhibition in the Brown-Peterson short-term memory paradigm. In both experiments, different groups of 4 words were presented on each of 6 trials, and recall was tested on each trial following a rehearsal-prevention period. Electrodermal activity was monitored throughout. The taxonomic category of words was the same throughout Experiment 1 (N = 96) for control groups, whereas for experimental groups, trial 5 consisted of words from a different category. In Experiment 2 (N = 96), taxonomic category was the same on all trials for all groups. However, intertrial intervals (ITIs) were either short or long, and for experimental groups, the trial 5–trial 6 ITI was either shortened or lengthened. The results of both experiments indicated that decline in recall performance across trials 1–5 was accompanied by a decrease in skin conductance response (SCR) magnitude. The change in taxonomic category in Experiment 1 produced both improved recall and increased SCR magnitude. The results of Experiment 2 indicated that both recall performance and SCR magnitude declined more slowly with long than with short ITIs. Moreover, an increase in ITI produced improved recall and increased SCR magnitude. However, although a decrease in ITI produced a decrement in recall performance, it had no effect on SCR magnitude. The results are discussed in terms of current theories of habituation and proactive inhibition in short-term memory.