Heart-rate change as a measure of verbal storage and retrieval

Heart rate and respiration were monitored while the subject listened for the appearance of a target sentence in a subsequent block of text. In two-thirds of the trails, the target sentence was altered by major or minor changes in wording, and the subject was asked to indicate whether or not a change had occurred. Heart rate preceding the first appearance of correctly recognized target sentences showed a steeper acceleration than heart rate preceding incorrectly recognized sentences. Mean heart rate during the correctly recognized embedded sentences showed a steeper deceleration than was present when the wording change was not recognized. Respiration amplitude decreased signifidantly discriminate between hits and misses, and did not correlate with change of heart rate. It was concluded that falling heart rate may be triggered by a shift in style of listening set in motion when the subject attends more closely to the specific words in the sentence as opposed to its underlying meaning.