Implicit and Explicit Drug Motivational Processes: A Model of Boundary Conditions

Introduction

The inveterate smoker may smoke cigarette after cigarette without being aware of deciding to smoke or without paying much attention to the act of smoking (Tiffany, 1990). Conversely, when making a quit attempt, the individual may agonize over whether or not to smoke and even go to elaborate lengths to secure a cigarette. Indeed, relapse cigarettes are often stolen (Brandon et al., 1990). Similarly, an alcohol-dependent individual may rather automatically consume a drink set in front of him or her, or go to elaborate lengths to distill or ferment alcohol to drink.

These observations are consistent with the notion that addictive behavior is supported by different types of information processing. Some of this information processing must be implicit: that is, occur fairly automatically without significant awareness. Other processing, however, must be explicit: that is, be planful and available to awareness. The model proposed in this paper is an attempt to suggest mechanisms and structures that are involved in both implicit and explicit processing of drug motivational information, and to propose when and how these mechanisms are recruited. In what follows, we first present a brief outline of our [Page 234]proposed model. Following this, we review research on negative and positive reinforcement mechanisms that establish the potent but often implicit, drug-use motivation among dependent drug users. Next, we integrate basic cognitive neuroscience research on the cognitive control of behavior to understand how boundary conditions are imposed on these implicit motivational processes via the recruitment of attention (i.e., what constrains their occurrence and influence). Finally, model implications are proposed to guide theory and research on drug-use motivation and craving.

Brief Outline of Model Tenets

We propose the following five tenets about drug-use motivation, drug-craving, and actual drug use:

• 1.
  Drug-use motivation is established via both negative and positive reinforcement mechanisms.
• 2.
  Once established, drug-use motivational processes often operate implicitly. In other words, the activation of drug-seeking or administration behaviors can occur automatically without the need for attention or extensive conscious awareness. The drug user may not necessarily be aware of the motivation to use drugs, the cues that elicited the motivation, or even the drug-administration behavior itself.
• 3.
  Drug-use motivational processes will become explicit (i.e., the person will be aware of the urge to use drugs) in situations where cognitive control attentional resources are recruited. We will reserve the term “drug-craving” to describe this conscious awareness of an urge to use drugs.
• 4.
  Basic research elucidates setting events for the recruitment of cognitive control. These include response conflict (i.e., concurrent activation of competing behavior responses), unfavorable outcomes (e.g., performance errors, negative feedback, pain, or other conscious distress), unexpected reward or punishment, and novel situations in which stimulus-response associations have not been previously established.
• 5.
  Cognitive control can be recruited to either support or inhibit drug use. When pursuing either drug abstinence or restriction of drug use, however, cognitive control is critical to overcome drug-use motivation and bias behavior toward nondrug-use behaviors. Therefore, explication of the factors that affect the cognitive control of drug-use motivation is clinically important.

‘Implicit” Drug Motivation