Study the brain mechanism of the influence of fear emotional stimuli on time perception

Time is one of the basic dimensions of human existence
.

Unlike the precise time recording of a clock, subjective time can be distorted by many factors, especially emotions
.

As a special type of emotion, fear emotional stimulus affects our perception of time
.

Under normal circumstances, people feel that time passes very slowly when facing fear scenes (such as the scene of a car accident), but when fear emotional stimuli are unpredictable (such as uncertain electric shock stimuli), subjective time compression occurs
.

In the latest study, Fu Xiaolan's research group at the State Key Laboratory of Brain and Cognitive Sciences explored the regulatory effects of unpredictable fear emotional stimuli on time perception and its neural mechanisms through EEG technology
.

The study adopted a two-factor mixed design of emotional stimulus type (fear, neutral) × anticipation (predictable, unpredictable), and the task of the participants was to estimate the interval time (Figure 1)
.

Behavioral results show that unpredictable fear pictures have the strongest time compression effect compared to other conditions
.

Figure 1.
Experimental process The most influential Scalar Expectancy Model in the field of time perception divides the time processing process into three stages: clock, memory, and judgment
.

The clock phase includes three parts: pacemaker, switch and accumulator
.

When the timing starts, the switch is closed, and the pacemaker sends time pulses to the accumulator at a certain frequency
.

When the timing ends, the switch is turned off and the pulse stops accumulating
.

The number of pulses accumulated in the accumulator is used to characterize the length of the time interval
.

The memory stage is composed of working memory and reference memory
.

The time information in the accumulator is transferred from the working memory to the reference memory at this stage
.

Finally, in the judgment stage, the individual compares the current time interval in the working memory with the time representation in the reference memory to make a time judgment
.

The results of the study show that the CNV EEG components that characterize the clock phase are not different in different expected fear and neutral pictures
.

Compared with the appearance of the picture (when the picture is locked), both the unpredictable fear and the predictable fear picture induce a greater P1 component
.

This shows that in the early stage of image processing, it has nothing to do with the time compression effect, and the fear of emotional stimuli will automatically capture attention
.

Interestingly, for the LPP component in the late stage, the unpredictable fear picture induces the largest volatility (Figure 2)
.

This is consistent with the behavioral outcome model, revealing that the time compression effect of the unpredictable fear emotion stimulus occurs in the memory rather than time perception stage
.

Figure 2.
Time-domain results of image locking.
Time-frequency results show that in the time window of LPP (200-600 milliseconds), unpredictable fear images induce the largest delta-theta rhythm energy, which is the time compression of rhythms and behaviors.
The quantity is negatively correlated (Figure 3)
.

It further proves that the unexpected fear stimulus interferes with the memory stage of time processing, resulting in the compression of subjective time
.

Figure 3.
Time-frequency results of picture lock time.
To sum up, this study provides empirical evidence for emotional regulation of time perception, and optimizes and expands the scalar timing theory
.

Dr.
Cui Qian (graduated) of the Institute of Psychology is the first author of the paper, and the associate researcher Zhao Ke and researcher Fu Xiaolan of the Institute of Psychology are the corresponding authors
.

The research results have been published online in Neuropsychologia
.

Paper information: Qian Cui, Mingtong Liu, Chang Hong Liu, Zhengkun Long, Ke Zhao, Xiaolan Fu (2021).
Unpredictable fearful stimuli disrupt timing activities: Evidence from event-related potentials, Neuropsychologia.
https://doi.
org/10.
1016 /j.
neuropsychologia.
2021.
108057 Source: Fu Xiaolan Research Group, State Key Laboratory of Brain and Cognitive Sciences