The role of emotions has been debated over the years, with some claiming that they are “bad for our peace of mind” (Skinner, 1948), and others arguing that they are important for our “physical or social survival” (Keltner & Gross, 1999).
Emotions can be defined as states induced by the occurrence, termination, or omission of rewards or punishments. A reward increases the probability of emission of an emotional response on which it is contingent, while a punishment decreases the probability of such a response (Rolls, 1990). Several functions of emotions support the hypothesis of these states as crucial for human survival.
First, emotions can help our bodies optimise the body state for different types of action, including fight, flight, feeding, and mating, by generating corresponding autonomic and endocrine responses (Levenson, 1992). Priming the body for action has been theorised to play a critical role in human survival by increasing performance to avoid and combat threats that pose danger to the fitness of the species (Mobbs et al., 2015).
Second, emotional stimuli that signal a potential threat or reward are more likely to capture the attention of an individual, optimising the selection of information relevant to survival for further processing. For example, a study showed that, when asked to search for discrepant fear-relevant pictures in a matrix of fear-irrelevant pictures, fear-relevant pictures such as snakes or spiders were found more quickly by participants than fear-irrelevant ones, such as flowers or mushrooms (Öhman et al., 2001). Thus, emotional stimuli related to recurrent survival threats in the environment may have been selected by evolution to automatically trigger the attention.
Third, emotions may act as a driver to actively seek or avoid a particular stimulus, by helping encode behaviours that promote reproductive success through primary rewards or punishments, which individuals will work to avoid or obtain. The behaviour can be selected either through primary or unlearned rewards and punishments (Rolls, 2000), or through pavlovian-type stimulus-reinforcer association learning (Holmes et al., 2010). In both cases, the type of emotion a stimulus induces will determine whether or not the behaviour of approach or avoidance is selected by the individual. This flexible interface between sensory inputs and action outputs is fundamental to human survival.
Emotions also play a central role in the cognitive evaluation, storage, and recall of memories (Rolls, 2000). They impact the evaluation of events by focusing on the encoding of emotional stimuli over neutral stimuli (Burke, 1992). This is particularly salient in the “weapon focus effect” (Loftus, 1979; Steblay, 1992), where eyewitnesses consistently over-focus their attention on the weapon held by the criminal—a behaviour likely to increase their chances of survival during the event—leading to impaired memories of other peripheral details after the event.
Emotions can also help individuals select the most relevant information from an event for further storage: there is evidence that memories from neutral stimuli decrease over time, but memories from emotional stimuli remain the same or improve (Baddeley, 1982). Furthermore, emotions can improve the ease with which memories are recalled.
In particular, the mood-congruence effect allows individuals to retrieve memories more easily when they have the same emotional content as their current mood (Bower, 1981), and the mood-dependence effect allows individuals to retrieve memories more easily when their mood at the time of encoding is similar to their current mood (Smith & Vela, 2001). The way emotions affect the processing, storage, and access to certain memories may be advantageous from a survival perspective in helping generate the optimal behaviour when faced with similar stimuli in the future.
Lastly, emotions are central to human communication and social bonding. For example, facial expressions, which are universal across human cultures, are used to communicate emotions such as fear, happiness or disgust, and serve as a useful mechanism to communicate information to others about a stimulus they haven’t experienced themselves (Ekman, 2993; Keltner et al., 2000).
Emotions also encourage social bonding through empathy (Watt, 2005), for example between a mother and her infant, with numerous studies showing a higher maternal response to a mother’s own infant crying (Swain, 2008).
While evidence shows the crucial role of emotions for human survival, the importance of cognitive appraisals associated with specific emotions to produce appropriate behaviour for fitness and survival of the species cannot be understated. Emotional states result from the interpretations and explanations of an individual’s circumstances, even in the absence of an intrinsically emotional stimuli (Scherer et al., 2001), and human survival relies on a complex combination of physiological and cognitive processes.
References:
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