Narcissistic and Dependent Behaviors in an Iterated Prisoner’s Dilemma Game

ABSTRACT

Interpersonal formulations are used to define, understand, and diagnose personality disorders. The accuracy of these formulations rests on a clear understanding of how those with personality pathology behave in social situations. To test these formulations, we conducted 4 experiments across 2 studies examining how trait dependence and narcissism interact to influence interpersonal functioning. The studies provided evidence for the interpersonal perspective, validated the measures used to describe self-report and/or expert judgment assessments. However, the studies also raise the question: “Do those with personality disorders behave in accordance with self-reports and expert judgments?” The answer stands to greatly improve interpersonal formulations of personality pathology.

Keywords

Narcissism, Dependence, Personality Disorders, Interpersonal Functioning, Prisoner’s Dilemma

INTRODUCTION

Personality disorders are largely understood by the specific interpersonal difficulties that profoundly affect the individual and their relationships with others. This is supported by numerous large-scale studies revealing that personality disorders are linked to distinct patterns of interpersonal dysfunction. It is also reflected in the current DSM-5-TR definitions of many personality disorders. For example, narcissistic personality disorder is defined as a pattern of grandiosity, need for admiration, and lack of empathy. Dependent personality disorder is defined as a pattern of submissive and clinging behaviors that reveal an excessive need to be taken care of.

The integration of behavioral economics into the study of personality pathology has helped answer this question. Economic games provide objective and controlled environments in which participants can reveal their interpersonal styles. However, they are not susceptible to the same biases that often plague self-report measures.

You and the other participant will play using a magic machine. Both of you will begin each round with 1 token (worth $2.00). If one of you puts in a coin, the other participant gets three coins – and vice versa. The decisions that you make will affect your and the other participant’s earnings in the game. Any money you and the other participant earn will be paid to you at the end of the game.

The other participant will play with you for the same game several times with another Prolific participant. Although the story behind the game is fictional, the earnings are real. The decisions that you make will affect your and the other participant’s earnings in the game. Any money you and the other participant earn will be paid to you at the end of the game.

TRAIT PERSONALITY

The self-report measures of trait dependency and narcissism that were brief and applicable to both clinical and non-clinical samples. Trait dependency was measured using the Dependent Personality Questionnaire. In the NPI, participants are presented with eight questionnaire items and must rate the extent that it applies to them on a 4-point scale ranging from yes, definitely to no, not at all. Example items include “I am an independent person” and “I rely a lot on my family and friends.” Potential scores in the DPQ range from 1 to 8.

RESULTS

When entering DPQ as a predictor (See Table 1), we found that trait dependency was associated with an increase in cooperation (X² (1) = 5.151, p = .023). In contrast, there was no influence (X² (1) = 1.389, p = .239).

Figure 4 once more illustrates the predicted probability of cooperation for predictors from the generalized estimating equation model (Narcissistic Personality Inventory and iteration). Includes predicted probabilities for Low NPI (1 standard deviation below the mean), mean NPI, and High NPI (1 standard deviation above the mean).

DISCUSSION

We found increased rates of cooperation among participants with trait dependence and narcissism in response to predetermined strategies in an iterated prisoner’s dilemma. This supports our hypotheses. Trait dependency was associated with increased cooperation in later iterations (X² (1) = 19.186, p < .001). This predicted probability model is shown in Figure 5.

CONCLUSION

Several aspects of our sample and methodology are important to address. First, the use of economic games to assess interpersonal functioning provides a unique perspective on personality pathology. Future research should consider the implications of these findings for understanding narcissistic and dependent personality disorders.

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