The Role Of Alertness On Time Perception

Perception of brief event durations is fundamental to a range of human perceptual and motor activities that include motor control in walking, speaking, playing music, driving a car, and participating in sports. Temporal illusions, in which the experience of time is not isomorphic to physical time, have long been reported in daily life as well as in psychophysical studies (Allman & Meck,2012; Wittmann, Van Wassenhove, Craig,& Paulus,2010). For instance, emotionally aversive events are perceived to last longer than their physical duration (Droit-Volet, Fayolle,& Gil,2011; Droit-Volet & Meck,2007; Gil & Droit-Volet,2011; Grommet et al.,2011; Wittmann & van Wassenhove,2009). Studies have also documented that stimuli with larger magnitudes, intensity, and complexity expanded perceived duration, whereas stimuli that are repeated, have high probability, and non-salient compressed time (Birngruber, Schroter,& Ulrich,2014; Eagleman,2008; van Wassenhove,2008). Although the mechanisms of temporal illusions are still under debate, attention and arousal have consistently been proven to be key factors that can influence time perception (Block& Zakay,1996; Droit-Volet & Meck,2007; Merchant, Harrington,& Meck,2013; Zakay, 1989; Zakay & Block,1996,1997a).Attention can be divided into two aspects:selective and nonselective alerting components. The former represents the selection dimensions, i.e., focused and divided attention, whereas the latter represents the intensity dimensions, i.e., alerting and sustained attention (Posner & Petersen,1990; Robertson, Mattingley, Rorden,& Driver, 1998; Sturm & Willmes,2001; Weinbach & Henik,2011). Most studies focused on the effects of the selection aspects of attention on time perception (J. T. Coull, Vidal, Nazarian,& Macar,2004; Hemmes, Brown,& Kladopoulos,2004; Henry, Herrmann, & Obleser,2013; Liu et al.,2013; Ulrich, Nitschke,& Rammsayer,2006). The internal clock model states that the higher the amount of attention focused on time, the more pulses accumulated. Empirically, people judge a certain duration to be longer when they allocate more attention to the target duration; whereas any attention that shifts from the target duration leads to shorter estimates (Buhusi & Meek,2005; Coull, Cheng, & Meek,2011; Coull et al.,2004; Gibbon, Church,& Meek,1984; Meek & Church,1983; Shi, Church,& Meek,2013; Treisman,1963). However, little is known about the role of the nonselective alerting component of attention in the processing of time perception.Alerting, a nonselective component of attention, refers to a state of general readiness that enhances processing of a stimulus and initiation of a response (Posner, 2008). There are two types of alerting; i.e., phasic alerting, which is specific to a task, and intrinsic alerting, which is general cognitive arousal (Raz & Buhle,2006). The alerting mentioned in this study is specified as phasic alerting. This ability can maintain and increase response readiness for a forthcoming stimulus without any specific prior selection. Phasic alerting is considered as the basis for operations such as orienting and selective attention (Finke et al.,2012; Husain & Rorden,2003; Sturm & Willmes,2001).The paradigm often used to study phasic alerting is measuring how an infrequent, unpredictable warning signal preceding the presentation of a stimulus affect subjects’response time (RT). Participants can maximize their alerting efficiency to prepare for the impending stimulus because of the alert of the warning signal. Previous studies have showed that when a stimulus is presented followed by a warning signal, the RT of participants is substantially faster compared to when no such warning is given (Fan, McCandliss, Fossella, Flombaum,& Posner,2005; Nebes & Brady,1993; Robertson et al.,1998).Not only different alerting state has an impact on the perceptual processing speed, visual conscious perception, and time perception of children (Droit-Volet,2003; Finke et al.,2012; Kusnir, Chica, Mitsumasu,& Bartolomeo,2011; Ellen Matthias et al., 2010; Weinbach & Henik,2012), but also the different individual alerting efficiency influences human behavior (DeGutis & Van Vleet,2010; Leproult et al.,2003; Posner, 2008). For instance, individual differences in alerting also impact the cognitive process (Liu, Yang, Chen, Huang,& Chen,2013). Alerting efficiency can serve as one of the indicators in the selection of athletes, pilots, and bus drivers (Brown, Guskiewicz,& Bleiberg,2007; Petroczi & Aidman,2008; Tafti, Besset,& Billiard,1992).To the best of our knowledge, little study has explored how alerting efficiency influence an individual’s time perception. Thus, we used six experiments in four studies to explore the cognitive and neural mechanisms of the modulation of alertness on time perception. (1) Individual alerting efficiency modulates time perception. (2) Warning Signals and Time Perception. (3) Neural time course and neural oscillation mechanisms of the modulation of alertness on time perception. (4) Neural activation patterns of modulation of alertness on time perception.(1)We used two experiments to investigate how alerting mediated time perception, with each experiment including two tasks in the Study 1. The Attentional Networks Test (ANT) allows assessment of the efficiency of attentional networks involved in the distinct functions of alerting, orienting, and executive attention (Fan, McCandliss, Fossella, Flombaum,& Posner,2005; Fan et al.,2002; Posner & Petersen,1990). We evaluated the individual differences in alerting efficiency through the ANT in two experiments. In Experiment 1, the temporal bisection task was used to explore the individual differences in alerting efficiency. In Experiment 2, the time generalization task was used to further validate the reliability of findings in Experiment 1. The results indicated that subjects in the high alerting efficiency group overestimated interval durations and estimated durations more accurately compared with subjects in the low alerting efficiency group. The two experiments showed that the sensitivity of time was not influenced by individual alerting efficiency. Based on previous studies and current findings, we infer that individual differences in alerting efficiency may influence time perception through modulating the latency of the attention-controlled switch and the speed of the peacemaker within the framework of the internal clock model.(2) Two experiments were used to explore the influences of warning signals of different modality on duration perception of visual and auditory modality. In Experiment 4, we used the paradigm which combined the warning signals of visual and auditory modality with visual temporal bisection task to explore the influence of alerting cue on visual time perception. In Experiment 5, we used the paradigm which combined the warning signals of visual and auditory modality with auditory temporal bisection task to explore the impact of alerting cue on auditory time perception. The results in Experiment 4 showed that subjects tended to overestimate interval duration with a visual alerting cue or an auditory alerting cue compared to without an alerting cue, and there were no difference on temporal sensitivity between two conditions. The results in Experiment 5 showed that subjects not only tended to overestimate interval duration but also improved the temporal sensitivity with an auditory alerting cue compared to without, but the visual alerting signal has no impact on auditory temporal perception. These results indicated alertness might have an impact on the latency of switch in the visual temporal information processing, and the alerting could speed up the internal pacemaker and reduced the latency of switch in the auditory temporal information processing. And the results also suggested the mechanisms of visual time and auditory time was distributed.(3) Experiment 5A and Experiment 5B were run to explore the neural time course and neural oscillation mechanisms of the modulation of alertness on time perception. The ERP analyses showed that alertness influenced time perception by modulating the amplitude of contingent negative variation (CNV) in encoding phase and comparing phase. Moreover, the alertness influenced the comparing phase of time perception through modulating the latency of CNV. The time-frequency analyses showed that alertness influenced time perception by modulating the magnitude of alpha-band ERSP. These results indicated that alertness can optimize attention on the processing of temporal information, lead to encoding and comparing the temporal information more easily.(4) We combined the warning cue paradigm with temporal comparison task and the used technology of functional magnetic resonance imaging (fMRI) to explore the neural activation patterns of modulation of alertness on time perception. The results showed that inferior frontal gyrus (IFG) and middle frontal gyrus (MFG) were more positive activated in the alerting signal condition in the encoding phase of time perception. Superior frontal gyrus (SFG) and supplementary motor area (SMA) were more negative activated in the alerting signal condition in the comparing phase of time perception. The activation of IFG was correlated with the modulation of attention, and the activation of SFG and SMA was correlated with the cognitive executive control and motor control, respectively. These results indicated alertness influenced time perception by modulating the activation of IFG in encoding phase, and the activation of SFG and SMA in comparing phase.We systematically explore the role of alertness on temporal information processing by using four studies. How individual alerting efficiency modulates time perception? The influences of warning signals of different modality on duration perception of visual and auditory modality. Neural time course and neural oscillation mechanisms of the modulation of alertness on time perception. Neural activation patterns of modulation of alertness on time perception. These studies showed that the alertness may be play a more fundamental role in the temporal processing.