Vigor represents a novel theoretical framework able to shed new light on the economic notion of individual preference. According to Shadmehr and Ahmed (hereafter, the authors), vigor can be used to quantify individual preferences, which, in standard economic theory, do not admit a cardinal representation but only an ordinal one. Indeed, although, in standard economic theory, agents are only able to compare and rank alternatives (so as to indirectly “reveal” their optimum, i.e., Samuelson, Reference Samuelson1948), vigor can provide a continuous scale for a direct measurement of subjective value, according to the general hypothesis that the vigor of movements toward things is a proxy of how we value them.

The hypothesized isomorphism between vigor and subjective value is a powerful idea. As such, it should be scrutinized through the arguments of one of the most heated debates in the economics of this past century: precisely, the debate about the nature of subjective value and individual preferences. A significant innovation, dialectical in this debate, was carried out by Herbert A. Simon through the notion of bounded rationality (foundational for behavioral economics), as an alternative to perfect rationality of homo oeconomicus (assumed in standard economic theory). Simon's critique relies on the argument that human beings are not maximizers, but satisficers, where satisficing is a portmanteau of “satisfice” and “suffice”: Economic agents do not compare choice options so as to select their optimum, they simply choose the first available alternative that meets their aspiration level (Gigerenzer & Selten, Reference Gigerenzer and Selten2002; Simon, Reference Simon1956). For instance, when we look for a restaurant in a new city, we plausibly choose the first one that is acceptable to us – it reaches the threshold of our own aspiration level – instead of comparing (all) the restaurants of the city. We are aware that, probably, there are better restaurants we are not considering (and, a fortiori, we are not comparing), nevertheless this rule works.

If we look at individual preferences through the lens of bounded rationality, we realize that conflating vigor and subjective value is not a neutral idea, as standard economic theory could suggest, and as the authors hypothesize. The central intuition of vigor, according to which (in the authors' own words, p. xi, emphasis added) “we move faster toward the things that we value more,” takes on a different meaning if aspiration levels come into play. More than what? we could ask. We can posit, as the authors do, that we move faster toward the things we value more in absolute terms (upper bound), but, more conservatively, we could hypothesize that we move faster toward the things that surpass our aspiration level (lower threshold). Very importantly, the demarcation between an upper bound (assumed in standard economic theory) and a lower threshold (assumed in bounded rationality) is not a matter of degree on a continuous scale. As vehemently remarked by H. A. Simon on several occasions, aspirational levels do not require a theoretical consistency with sub-optimality, being the notion of satisficing a tout-court alternative to both optimality and sub-optimality (e.g., Simon, Reference Simon1996).

The authors explicitly ascribe the theoretical scope of vigor to standard economic theory stating that “choices are determined by the computation of a utility, a logical process of deliberation that results in the maximization of the gain ascribed to the utility” (p. 69). Indeed, in standard economic theory, choices require the perfect rationality of economic agents, which is instantiated in an omnibus comparison of alternatives based on monotonic preferences. Actually, such instantiation is problematic, considering that transitivity of preferences is often violated (Tversky, Reference Tversky1969; see also Regenwetter, Dana & Davis-Stober, Reference Regenwetter, Dana and Davis-Stober2011). The existence of an omnibus comparison of alternatives based on monotonic preferences is a demanding assumption – axiomatically postulated in standard economic theory – that the authors embrace as vigorously as uncritically. And this assumption is precisely the one that bounded rationality tries to overcome with a more realistic (where “realistic” is the equivalent of cognitively plausible) explanation of how choices are made de facto in ecological settings.

But, if we think that bounded rationality and aspiration levels jeopardize the theoretical scope of vigor as a proxy of subjective value, we could be wrong. Far from playing only the role of pars destruens, the notion of aspiration levels is surprisingly consistent with vigor, although the authors do not explore this theoretical link. The idea of utility proposed by the authors – “Utility of an action may be defined as the reward expected when the action is completed minus the effort required to complete the action, divided by time to acquire the reward” (p. 13, emphasis added) – articulates a fundamental facet of aspiration levels: economic agents conjointly evaluate the expected reward and the costs related to its attainment. Put differently, economic agents seek a satisficing balance between “what they can get” and “to what effort,” where the effort is affected by the limited endowment of time, information, and computational capabilities (as postulated in bounded rationality, Simon Reference Simon1955, Reference Simon, Eatwell, Milgate and Newman1987). Although in standard economic theory, efforts are ruled out (or, they are modeled as monetary costs, expressed in terms of budget constraints), in bounded rationality and its articulation of ecological rationality (e.g., Gigerenzer & Selten, Reference Gigerenzer and Selten2002; Todd & Gigerenzer, Reference Todd and Gigerenzer2012), efforts are theoretically central, being related to the procedural dimension of rationality (Simon, Reference Simon, Kastelein, Kuipers, Nijenhuis and Wagenaar1976) and, in particular, to search: efforts signal how much an available alternative is still not worth – the lower threshold is not reached – so that (the action of) search must continue. Using again the restaurant example, we easily realize that in a new city we will keep on searching for a restaurant until we find one that meets our aspiration level.

Although the authors speculate on individual preferences, sitting in the realm of standard economic theory, we believe that bounded and ecological rationality represent the theoretical domains of behavioral economics, on which vigor could have a significant impact for future research. Indeed, a core argument of vigor – the effort of making movements and the benefit of acquiring rewards are conceived within a unitary theoretical framework – is able to articulate the nature of ecological balance (central in bounded and ecological rationality) between aspiration level (the minimum expected reward) and cost of search (the effort made). Using again our previous example about the restaurant, we realize that the rule of choosing the first restaurant that meets our aspiration level, works precisely because it is based on an acceptable balance between efforts and reward. Speculatively, efforts could be considered the “psychophysiological” price to pay for a specific reward. Note that, in bounded and ecological rationality, the ecological balance between efforts and reward is achieved de facto through the use of heuristics, which represent adaptive tools able overcome the limited endowment of time, information and computational capabilities of the economic agents (Gigerenzer, Reference Gigerenzer2008). Again with the restaurant example: asking local people or looking at parked cars are common “rules of thumb” used to make inferences about restaurants.

Studying economic choice in ecological settings is a pillar of bounded and ecological rationality, but it is not a mark of standard economic theory. Strangely, despite the authors’ consideration of how ecological dimension enters economic choice (in particular, they discuss modal representations of the environment, looking at salience as an alternative to utility maximization, in sect. 2.7) they do not explore this aspect further. If we discard the demanding assumptions of omnibus comparison and maximization (connoting standard economic theory, endorsed by the authors) and, more conservatively, we contemplate the existence of aspiration levels – where subjective value is situated in the neighborhoods of an ecologically salient lower threshold – we will mitigate the Panglossian risk of conflating the adaptive scope of vigor into the teleological need for optimality.