1. Uncertainty
Certainty is important to humans as it provides a sense of safety, happiness, and fulfillment [1]. However, uncertainty is a reality, and people experience uncertain events frequently in their daily lives [2]. As uncertainty is frequently associated with anxiety and discomfort [3], individuals often adopt coping strategies to manage uncertainty. The strategies are avoidance and aversion to the uncertainty, and then not deliberately encounter it. Paradox for dealing with the uncertainty is that individuals often approach it intentionally. This study aimed to investigate the use of approach motivation as a strategy to manage uncertainty and explore the differences in its use among individuals with varying levels of uncertainty tolerance. We conducted an event-related potential (ERP) study to measure approach motivation and investigate the cognitive stages involved in its use.
1.1 Definition of uncertainty
Uncertainty arises when individuals are faced with ambiguous events. Although the specific definition of uncertainty often depends on its source, incomplete or conflicting information is widely accepted as a central feature of uncertainty [4]. Uncertainty may stem from the absence of external information or from an individual's internal ignorance of information [5]. The processing of uncertainty may involve various processes, including sensory encoding, state assessment, rule recognition, and motor control [6]. In the human brain, uncertainty may activate several regions, such as the anterior cingulate (encoding the level of sensory uncertainty), the amygdala (indicating surprise), and the parietal cortex (encoding the likelihood of reward) [6, 7].
1.2 Theories related to the sense of uncertainty
Since everyone has a fundamental need for certainty, the reduction of uncertainty has become a widespread motivation for individuals. The principal theories encompassed in the strategies for coping with uncertainty include the Uncertainty Management Model, Uncertainty Identity Theory, Uncertainty Reactive Approach Motivation Theory, and the Meaning Maintenance Model, which integrates these theories.
The uncertainty management model, proposed by van den Bos [3], posits that individuals mitigate uncertainty by defending their cultural worldviews, emphasizing the compensatory strategies of cultural worldview defenses in response to self-imposed uncertainty. The central concept is that when individuals experience excessive uncertainty that jeopardizes their sense of survival, they develop a need for order and predictability. Cultural worldviews can instill order and rules into the social environment perceived by individuals, providing a sense of stability. Consequently, individuals tend to exhibit behaviors aligned with their cultural worldviews while distancing themselves from other threatening cultural worldviews [8].
The uncertainty-identity theory, proposed by Hogg [9], is a social psychological theory that underscores the dynamic role of self-uncertainty in in-group relationships and group interactions. The theory posits that individuals mitigate uncertainty about themselves, their lives, and their futures through self-categorization and group identification when facing high uncertainty, highlighting the need for belonging and acceptance as individuals seek certainty [10]. For instance, Van Prooijen et al. confirmed that in a state of uncertainty, individuals are more inclined to avoid standing out as prominent members within a group [11].
The uncertainty reactive approach motivation theory, mainly elaborated by Mcgregor, suggests that individuals who feel threatened by self-uncertainty respond to self-uncertainty by converging on higher goals such as religion and ideal beliefs, showing the role of higher-level needs in reducing uncertainty. For example, a study confirmed the uncertainty response approach theory of motivation, finding that individuals experiencing high uncertainty anxiety, and those with lower uncertainty tolerance showed a more fervent preference for religious beliefs [12].
The meaning maintenance model [13], integrates the previous strategies. The theory suggests that humans are innate meaning seekers with four main basic needs: the need for certainty, the need to belong, the need for self-esteem, and the need for spiritual permanence. When one of these needs (e.g., the need for certainty) is not met, individuals maintain the integrity of the meaning system by obtaining other types of needs (e.g., the need for belonging) through flow compensation.
All of the aforementioned uncertainty theories share a common core element: when individuals encounter uncertainty, they exhibit behaviors aimed at reducing it. This underscores the significance of seeking certainty in the human survival process.
2. Reduce uncertainty and approach motivation
People are always seeking certainty and avoiding ambiguous scenarios as much as possible because, in the vast majority of cases, uncertainty is an overwhelming experience [14, 15]. Uncertainty can cause anxiety and even impair cognitive functioning [16, 17], so when individuals perceive uncertainty, they take various measures to resolve it, e.g., reducing or acknowledging uncertainty [4]. Among them, reducing uncertainty is an important strategy and the focus of our study.
Prior research suggests that approach motivation plays a crucial role in alleviating uncertainty. Anxiety-induced uncertainty leads individuals to be passively motivated to approach, while personal uncertainty actively generates approach motivation through reinforcing cultural worldview defenses and pursuing personal ideals [12, 18]. Moreover, the activation of brain regions linked to approach motivation is associated with a higher sense of certainty and meaning [19], and a decreased response to risky stimuli [20], indicating that approach motivation may mitigate negative emotional and cognitive responses to uncertainty.
Moreover, numerous researchers have observed that individuals who lack a sense of control intensify their efforts to achieve goals, thereby triggering high approach motivation to counteract feelings of loss of control [21]. Given that both feelings of loss of control and uncertainty result in negative emotional experiences, individuals are driven to generate approach motivation to safeguard their sense of meaning and predictability in the world. Consequently, uncertainty is likely to elicit approach motivation in a similar manner to a sense of loss of control. This leads us to the hypothesis:
H1: Uncertainty has a positive effect on approach motivation.
3. The moderating effect of tolerance for uncertainty
3.1 Definition of Tolerance for Uncertainty
Tolerance for Uncertainty refers to individual differences in individuals' emotional, behavioral, and cognitive response tendencies in response to uncertain situations or events, and it is a stable personality trait [22].
Impact of Tolerance for Uncertainty
Cognitively, individuals with low uncertainty tolerance are inclined to perceive uncertainty as negative. Emotionally, uncertainty leads to increased frustration and stress for those with low tolerance. Behaviorally, individuals with low tolerance tend to exert control over their behavior to minimize uncertainty or its duration [23]. Consequently, individuals with low uncertainty tolerance are more likely to respond to uncertain events with an approach motive to attain a greater degree of certainty, thereby reducing discomfort induced by uncertainty. In summary, we propose the following hypotheses:
H2: Uncertainty tolerance moderates’ uncertainty-induced approach motivation, with lower uncertainty tolerance strengthening the positive effect of uncertainty on approach motivation.
4. Uncertainty and negative emotions
Numerous prior studies have demonstrated that uncertain events elicit more negative emotions than certain events, with substantial research supporting this assertion [3, 24]. According to uncertainty management theory, uncertainty tends to evoke intense emotions, making emotions a reliable indicator of uncertainty. Uncertainty is primarily linked to aversive emotions such as fear and anxiety [25]. Previous research has indicated that feedback-related negativities (FRNs) resulting from ambiguous feedback are akin to those triggered by negative feedback, suggesting their shared negative nature [26]. Several subsequent event-related potential (ERP) studies have examined the role of FRN and P300 in the outcome feedback phase of decision-making tasks [27]. Physiological findings from Wang Y.W. [28] in a repetitive trust game task revealed that loss feedback induced a more negative FRN component than benefit feedback during the feedback phase. Gu [29] investigated how self-affirmation influenced the way electrophysiological signals processed ambiguous feedback in a simple gambling task, and found that ambiguous feedback elicited a greater FRN than negative feedback. The prevailing explanation for this phenomenon is that ambiguous feedback is not only negative [30] but also uncertain, thus requiring additional cognitive resources for processing due to limited cognitive capacity [31, 32]. This leads to the hypothesis that: H3: Uncertainty feedback elicits significantly more negative emotions than loss feedback, and both significantly differ from gain feedback.
5. Selection of event-related points (ERPs) as a measure of approach motivation
According to the biphasic motivational account, approach motivation triggers increased activity in the left prefrontal lobe, whereas avoidance motivation triggers increased activity in the right prefrontal lobe [33]. The earliest findings of a link between left prefrontal asymmetry and approach motivation stemmed from a focus on patients with focal brain damage in the left or right hemisphere. Asymmetric frontal activity (AFA) seems to suggest that the left prefrontal lobe is involved in processing positive emotions and the right prefrontal lobe in processing negative emotions [34]. Whereas positive emotions tend to induce approach motivation, negative emotions tend to induce avoidance motivation [35]. In recent years, a number of studies have confirmed the link between left prefrontal EEG activity and motivation-related behaviors and emotions, including risky behavior, angry emotions, and strong goal orientation [36]. These findings suggest that the level of relative left prefrontal activation in individuals in angry mood states is influenced by the level of approach motivation.
In addition, the specific nodes and temporal windows that generate approach motivational neural activity were explored by examining two electrophysiological components triggered by the resultant feedback: feedback-related negativity (FRN) and P300, using the high temporal precision of ERP. FRN is a peak within 200-300ms after the presentation of the feedback stimulus brain waves whose source is localized near the anterior cingulate cortex (ACC), arising in the prefrontal region of the brain [37]. This electrophysiological component has a greater amplitude of negative waves following incorrect or negative events compared to correct or positive occurrences. P300 is a positively oriented wave that appears in the postcentral brain region approximately 300-600ms after the presentation of a feedback stimulus, and previous studies have shown that the P300 component is sensitive to risky decisions. One study designed a gambling task called "wheel of fortune" and applied event-related brain potentials (ERPs) to explore the processing of uncertain (risky and ambiguous) cues, and they found that unexpected cues elicited larger P300s under uncertainty [27]. These studies show that both risky and ambiguous conditions evoke a P300 component. Therefore, the present study was based on the neurophysiological mechanisms of approach motivation, and the FRN and P300 were used to observe the aversion and uncertainty produced by the subjects in the task, respectively, to examine the effect of uncertainty on approach motivation and its representation at the level of neural activity.