The dynamics of auditory memory under tension inducing conditions.

The retention of 'sounds of different pitch ranging from 700 to 2,000 Hz was investigated in previous study (1). We used the method of comparison of two stimuli following one another after an interval of 10, 20, 40, 80, 160 and 320 s. In various experiments the two compared sounds differed either in pitch, or in pitch and loudness. Retention did not change significantly at the intervals from 10 to 40 s. When the interval between stimuli reached 80 s, the number of errors rapidly increased. From the 80 s interval the longer the inter-stimulus interval the greater the number of errors. As shown in Fig. 1, similar results were obtained under three conditions: (i) the compared stimuli were equal in loudness and differed from each other only by one semitone (curve I); (ii) the stimuli differed from each other in pitch by two semitones and in intensity-the pattern stimulus was by 25 dB less intensive than the second stimulus (curve 11); (iii) the pattern stimulus was by 25 dB more intensive (curve 111). The fact that similar results were found in three different experimen-' tal situations points to the importance of that particular time interval between compared stimuli in the memory process, and suggests that it is connected with two different physiological mechanisms. It is possible that we are dealing here with a "switch-over" from one kind of memory mechanism to another. A verification of this hypothesis was undertaken in the reported experiment. We expected that the application of a tension-arousing factor in the break between the compared sounds would influence in the memory in a different way after an interval lasting up to 80 s than after