When confronted with a novel or unexpected stimulus, such as a sudden innocuous noise in an otherwise silent environment, humans and other animals orient toward the source of the stimulus. This “orienting reflex” is an expression of increased attention and has long been linked to specific components in the electroencephalography signal (Sokolov, Reference Sokolov1963). Novelty also drives a wide range of higher-order behaviors through diverse sets and intertwined neural mechanisms. For instance, novelty can promote spatial memory via changes in dopamine dependent long-term potentiation in rats (Wang, Redondo, & Morris, Reference Wang, Redondo and Morris2010), cue-evoked dopamine promotes associative learning in mice (Morrens, Aydin, Janse van Rensburg, Esquivelzeta Rabell, & Haesler, Reference Morrens, Aydin, Janse van Rensburg, Esquivelzeta Rabell and Haesler2020), novelty shapes salience memories via activity in the prefrontal cortex and basal ganglia in monkeys (Ghazizadeh & Hikosaka, Reference Ghazizadeh and Hikosaka2022), and, also in monkeys, basal forebrain neurons distinguish between novelty and familiarity in recognition memory tasks (Wilson & Rolls, Reference Wilson and Rolls1990). This is compatible with human imaging studies showing that novelty processing improves subsequent recognition memory via neural beta oscillations (13–25 Hz) (Steiger, Sobczak, Reineke, & Bunzeck, Reference Steiger, Sobczak, Reineke and Bunzeck2022), and the fact that novelty responses in the human substantia nigra (SN)/ventral tegmental area (VTA) are modulated by dopaminergic and cholinergic stimulation (Bunzeck, Guitart-Masip, Dolan, & Duzel, Reference Bunzeck, Guitart-Masip, Dolan and Duzel2014). Finally, environmental novelty enhances memory via co-release of dopamine from locus coeruleus axon terminals in the hippocampus (Takeuchi et al., Reference Takeuchi, Duszkiewicz, Sonneborn, Spooner, Yamasaki, Watanabe and Morris2016).

Although these findings help to clarify how novelty affects exploration and learning, the underlying motives remain unclear. From an evolutionary perspective, exploring the unknown can be advantageous for several reasons. First, it can help to reduce uncertainty in light of possible rewards and punishments (e.g., nutritious vs. poisonous foods, or harmful vs. harmless snakes, etc.). Second and along these lines, novelty-evoked exploration can promote cognitive and behavioral flexibility since it requires adaptation and possibly innovative solutions (e.g., learning how to open a coconut without losing the valuable milk). Third, together with potentially increasing genetic diversity and escaping current adverse living conditions, the exploration of novel environments can, therefore, increase the chances for survival both at an individual and group level. As a mechanism to realize motivated behaviors, computational modelling has offered a simple solution. By treating novelty as reward, the dopaminergic reward system creates an “exploration bonus,” which incentivizes exploration similar to how it motivates the search for rewards (Kakade & Dayan, Reference Kakade and Dayan2002). In line with this notion, contextual novelty changes reward representations in the human striatum (Guitart-Masip, Bunzeck, Stephan, Dolan, & Düzel, Reference Guitart-Masip, Bunzeck, Stephan, Dolan and Düzel2010; Wittmann, Daw, Seymour, & Dolan, Reference Wittmann, Daw, Seymour and Dolan2008) and the neural dynamics of reward anticipation (Bunzeck, Guitart-Masip, Dolan, & Düzel, Reference Bunzeck, Guitart-Masip, Dolan and Düzel2011). Together with the observation that monetary rewards accelerate the onset of neural novelty signals in humans (Bunzeck, Doeller, Fuentemilla, Dolan, & Duzel, Reference Bunzeck, Doeller, Fuentemilla, Dolan and Duzel2009), this further demonstrates the close empirical link between novelty processing and reward motivation.

From a psychological perspective, the motive to explore novelty relates to personality traits and corresponding current states. Specifically, the personality trait novelty-seeking positively correlated with hemodynamic activity in the SN/VTA elicited by novel cues (Krebs, Schott, & Düzel, Reference Krebs, Schott and Düzel2009). Moreover, the temporary and situational intrinsic motivation to acquire new knowledge, also referred to as state epistemic curiosity, drives long-term memory via the dopaminergic mesolimbic system (Gruber, Gelman, & Ranganath, Reference Gruber, Gelman and Ranganath2014; Kang et al., Reference Kang, Hsu, Krajbich, Loewenstein, McClure, Wang and Camerer2009). Trait epistemic curiosity, that is, the rather stable and consistent desire to acquire new knowledge, contributes to various aspects of motivation and performance in academic and professional contexts, including goal setting and learning (Litman & Mussel, Reference Litman and Mussel2013). The underlying principles of such higher-order curious behaviors can be described by reinforcement learning (RL)-frameworks in which novelty generates an intrinsic reward signal in addition to an extrinsic (primary) reward signal (Modirshanechi, Kondrakiewicz, Gerstner, & Haesler, Reference Modirshanechi, Kondrakiewicz, Gerstner and Haesler2023). By separating intrinsic (novelty-driven) from extrinsic (reward-driven) motivational processes, these RL-frameworks can also explain non-optimal behavior such as continuing to seek novelty even when novelty-seeking leads to distraction by reward-independent stochasticity (Modirshanechi, Xu, Lin, Herzog, & Gerstner, Reference Modirshanechi, Xu, Lin, Herzog and Gerstner2022) also referred to as “noisy-TV” problem (Aubret, Matignon, & Hassas, Reference Aubret, Matignon and Hassas2023). Importantly, neuroimaging supports the presence of separate intrinsic and extrinsic signals at the neural level (Filimon, Nelson, Sejnowski, Sereno, & Cottrell, Reference Filimon, Nelson, Sejnowski, Sereno and Cottrell2020).

Finally, disease-related and age-related brain changes, especially within the mesolimbic system and interconnected brain regions, impact on novelty exploration, motivation, and learning. For instance, age-related degeneration of the dopaminergic midbrain affects neural novelty signals and long-term memory performance (Düzel, Bunzeck, Guitart-Masip, & Düzel, Reference Düzel, Bunzeck, Guitart-Masip and Düzel2010), whereas iron levels and myelin content in the ventral striatum predict memory performance in older adults (Steiger, Weiskopf, & Bunzeck, Reference Steiger, Weiskopf and Bunzeck2016). More recent studies have pointed out that locus coeruleus integrity, associated with dopaminergic and noradrenergic neuromodulation, also plays a key role in learning novel information in healthy and pathological aging (Dahl et al., Reference Dahl, Mather, Düzel, Bodammer, Lindenberger, Kühn and Werkle-Bergner2019, Reference Dahl, Kulesza, Werkle-Bergner and Mather2023). Along these lines, behavioral, neurobiological, and computational changes in motivation-based exploration and learning have been identified in several neuropsychiatric conditions, such as attention deficit hyperactivity disorder (Véronneau-Veilleux, Robaey, Ursino, & Nekka, Reference Véronneau-Veilleux, Robaey, Ursino and Nekka2022) and psychotic disorders (Kesby, Eyles, McGrath, & Scott, Reference Kesby, Eyles, McGrath and Scott2018). In fact, in adolescents with high novelty-seeking scores, multimodal biomarkers predicted longitudinal risk behavior (including alcohol drinking) (Qi et al., Reference Qi, Schumann, Bustillo, Turner, Jiang and Zhi2021).

Taken together, novelty motivates a wide range of higher-order behaviors, especially learning and associated memory formation, and recent studies gave detailed insights into the underlying psychological, neurobiological, and computational processes across the lifespan. As such, we agree with Murayama and Jach that there are myriad unanswered questions, but we would like to stress that translational and interdisciplinary research has tremendously helped – and will help in the future – to further conceptualize the construct of motivation.