Short-term memory and effects of proactive interference on heart rate.

Abstract

40 subjects were required to memorize different word lists. Each list contained three words, and each list corresponded to one trial. The Brown-Peterson paradigm was employed to induce proactive memory interference. For the experimental group the first three lists belonged to a negative affective encoding category, while the fourth belonged to a different encoding category. The control subjects memorized words from mixed encoding categories. In the experimental group proactive interference built up over trials with the same encoding category of words, resulting in a poorer performance at recall, during the second and third trials, and progressive decrease in heart rate. On the fourth trial of the Brown-Peterson task, proactive interference ceased, resulting in better recall than the previous interference trials, concomitantly with an increase in heart rate. These results are discussed within the context of Lacey's hypothesis, according to which, heart rate should increase with cognitive activity requiring rejection of environmental stimuli.