The target article by Redish et al. presents a theoretical framework for addiction as arising from an array of vulnerabilities in the way in which individuals make decisions regarding behaviour. In the present commentary, I examine how several aspects of social interaction may exploit the vulnerabilities outlined by the authors.

Redish and colleagues argue that addiction can be viewed as a series of maladaptive choices, and that models of human decision-making can be employed to show how addictions may develop and be maintained. According to Redish et al., these vulnerabilities can lead to incorrect or inappropriate decisions regarding substance use, thereby leading to addiction. To support these positions, Redish and colleagues review a range of studies generally drawn from research on human decision-making, learning theory, and neuropsychology. The authors point out, however, that their theory may have implications for other theories of addiction, including social theories.

There have been numerous social theories of addiction in the literature. For example, social learning theory suggests that addiction may be the result of observation and mimicking of substance use and abuse in role models such as parents (Eiser Reference Eiser1985; Fischer & Smith Reference Fischer and Smith2008; Neiss Reference Neiss1993; Raskin & Daley Reference Raskin and Daley1991). In addition, a number of theories of addiction suggest that addictive behaviors are developed via affiliation with substance-using peers and others (Bloor Reference Bloor2006; Duncan et al. Reference Duncan, Duncan, Biglan and Ary1998; Jenkins Reference Jenkins1996; Wills et al. Reference Wills, Windle and Cleary1998). It seems reasonable to assume that social influence, and in particular social influence linked to substance use, may also exploit vulnerabilities in the decision-making system in the ways specified by Redish and colleagues. In particular, it may be argued that social influence may exploit three of the vulnerabilities proposed by Redish et al. – overvaluation of the expected value of a predicted outcome in the planning system (Vulnerability 4); incorrect search of situation–outcome relationships (Vulnerability 5); and misclassification of situations (Vulnerability 6) – in turn increasing the risk of addiction.

In describing Vulnerability 4, Redish and colleagues provide a neurochemical account of how the planning system can lead to an overvaluation of the value of a predicted outcome, via the pairing of a valued outcome (drug use) with some other valued stimulus. It is clear that social interaction might serve as a valued stimulus that, paired with drug use, could lead to an increase in the value of drug use, thereby increasing the risk of addiction. For example, several studies have shown that the initiation of substance use occurs most frequently in social situations (Clark et al. Reference Clark, Parker and Lynch1999; Galea et al. Reference Galea, Nandi and Vlahov2004; Kaplow et al. & Conduct Problems Prevention Research Group Reference Kaplow, Curran and Dodge2002M). Also, further studies have shown that adolescent substance use patterns are largely influenced by social context (Petraitis et al. Reference Petraitis, Flay, Miller, Torpy and Greiner1998; Schuckit et al. Reference Schuckit, Smith, Pierson, Danko, Allen and Kreikebaum2007; Wilcox Reference Wilcox2003). In addition, neuropsychological research has shown that social interaction and relationships may stimulate reward centers in the brain (Caldu & Dreher Reference Caldu and Dreher2007; Depue & Morrone-Strupinsky Reference Depue and Morrone-Strupinsky2005; Guroglu et al. Reference Guroglu, Haselager, van Lieshout, Takashima, Rijpkema and Fernandez2008; Walter et al. Reference Walter, Abler, Ciaramidaro and Erk2005), suggesting that the pairing of social interaction and substance use may lead directly to an overvaluation of substance use, thereby exploiting this particular vulnerability.

Vulnerability 5 involves a memory process by which certain situations may be more likely to lead to certain outcomes (i.e., drug use), because the memory of a valued situation-outcome pairing becomes more salient, blinding the individual to alternatives. Here again, social interaction may play a crucial role in exploiting this particular vulnerability. As mentioned previously, substance use and abuse often occurs in social situations, and individuals who are early (i.e., childhood and early adolescent) initiators of substance use, and thus at increased risk of substance dependence (e.g., Fergusson & Horwood Reference Fergusson and Horwood1997), are more likely to engage in substance use in a social context. Yet another way in which this vulnerability might be exploited is through the salience of social interaction as a cue for memory retrieval. A range of studies have shown that social information is more easily recalled, and that it has more complex and detailed relationships with other information in an individual's associative memory network (Clark & Stephenson Reference Clark and Stephenson1995; Leone Reference Leone2006; Reynolds & West Reference Reynolds and West1989; Walker-Andrews & Bahrick Reference Walker-Andrews and Bahrick2001). These considerations suggest that the social context in which substance use and abuse occurs may play a key role in exploiting vulnerabilities in the decision-making process related to memory.

Vulnerability 6, situation misclassification, occurs when individuals overgeneralize situations to other situations, despite changes in the nature of the situation. Thus, for example, drug users may be unable to change their drug-taking behavior despite negative consequences arising from their drug use. It could be argued that this vulnerability is exploited when individuals move from the use of one drug to another, more addictive drug, such as the progression of drug use via the gateway mechanism (Fergusson et al. Reference Fergusson, Boden and Horwood2006; Kandel et al. Reference Kandel, Yamaguchi and Chen1992; MacCoun Reference MacCoun1998). Under this explanation, individuals are more likely to move from drugs that have a lower risk of dependence (i.e., cannabis) to drugs with higher risks of dependence (e.g., cocaine, opiates, methamphetamine; Fergusson et al. Reference Fergusson, Boden and Horwood2006; Kandel et al. Reference Kandel, Yamaguchi and Chen1992). Fergusson and colleagues have argued that one of the main drivers of the cannabis gateway is social interaction, and that differential association with individuals who have access to a range of illicit drugs (such as drug dealers) increases the availability of other illicit drugs, thereby increasing the risk that an individual will use these drugs (Fergusson et al. Reference Fergusson, Boden and Horwood2006). In this way, generalization from one situation (cannabis use) to another situation (other illicit drug use), arising from social interaction, may lead to an inability to stop using drugs when symptoms of dependence arise from the use of other illicit drugs.

In summary, Redish and colleagues have developed a model that shows how individuals may make maladaptive choices with regard to substance use, leading to increased risk of addiction. It seems clear that social interaction plays an important role in exploiting these vulnerabilities, providing information that may inadvertently increase the risk that individuals will become substance-dependent.