Temporal Expectancy Modulates Alerting Effect

Alertness, as one of the three subsystems of attention, was not so much concerned as orienting and executive control. When a non-indicative warning signal was presented before an imperative stimulus, the response was faster. This facilitation was referred to as alerting effect. Furthermore, reaction time decreased as a function of the increasing fore-period, i.e., the interval between the warning signal and the imperative stimulus. This fore-period effect could disappear by manipulating the fore-period distribution. In previous studies regarding alerting effect, fore-period was inevitably involved in method used to measure alerting effect, and it was not taken into account. In the present study, we manipulated the temporal expectancy by arranging the warning signal-target stimulus onset asynchrony distribution into three experimental groups: non-aging, aging and accelerated-aging. Our results suggested that temporal expectancy could modulate the alerting effect. As temporal expectancy increased across the three groups, the alerting effect appeared later. However, temporal expectancy could not influence the magnitude of alerting effect. This put-off modulation tendency was similar in both the detection and discrimination tasks.As an alternative explanation of the non-specific preparation, trace conditioning attributed the fore-period effect to sequential effect. We further analyzed this hypothesis and refused to admit that sequential effect could interpret fore-period effect independently. Thus we confirmed that temporal preparation which involved in intentional behavioral optimization modulated alerting effect.