Rationale and objective The aim of this study was to investigate the possible facilitating effect of the partial NMDA receptor agonist D-cycloserine (DCS) on memory consolidation of conditioned... Show moreRationale and objective The aim of this study was to investigate the possible facilitating effect of the partial NMDA receptor agonist D-cycloserine (DCS) on memory consolidation of conditioned sexual responses and to examine the capability of DCS to reduce context-specificity of learning. Methods In a randomized placebo-controlled double-blind trial, 50 healthy females were exposed to a differential conditioning procedure. Two pictures of a male abdomen were used as conditional stimuli (CSs), of which one (the CS+) was followed by the unconditional stimulus (US), a genital vibrotactile stimulus. After the conditioning session on day 1, participants received either 125 mg of DCS or a placebo. The effects of DCS on affect, sexual arousal and US expectancy in response to the CS+ and CS- were examined 24 h after the conditioning procedure. Results A main effect of DCS was found on affect at the first test trials (p = 0.04, eta(2)(p) = 0.09), and a similar non-significant but trend level effect was found for sexual arousal (p = 0.06, eta(2)(p) = 0.07), which appeared to persist over a longer time (p = 0.07, eta(2)(p) = 0.08). Unexpectedly, ratings of positive affect and sexual arousal in response to both the CS+ and the CS- were higher in the DCS condition compared to the control condition, possibly indicating that DCS administration reduced stimulus specificity. Since the results did not show clear evidence for context learning, we were not able to test effects on context-specificity of learning. Conclusion Although largely inconclusive, the results provide tentative support for a facilitating effect of DCS on affect and sexual arousal in response to stimuli that were presented in a sexual conditioning procedure, however, no conclusions can be drawn about effects of DCS on sexual reward learning, since the design and results do not lend themselves to unambiguous interpretation. Show less
The present research examined whether cognitive load modulates the neural processing of appetitive, high-calorie food stimuli. In a functional magnetic resonance imaging (fMRI) study, participants... Show moreThe present research examined whether cognitive load modulates the neural processing of appetitive, high-calorie food stimuli. In a functional magnetic resonance imaging (fMRI) study, participants quickly categorized high-calorie and low-calorie food pictures versus object pictures as edible or inedible while they concurrently performed a digit-span task that varied between low and high cognitive load (memorizing six digits vs. one digit). In line with predictions, the digit-span task engaged the dorsolateral prefrontal cortex (DLPFC) when cognitive load was high compared to low. Moreover, exposure to high-calorie compared to low-calorie food pictures led to increased activation in the nucleus accumbens (NAcc), but only when cognitive load was low and not when it was high. In addition, connectivity analyses showed that load altered the functional coupling between NAcc and right DLPFC during presentation of the high-calorie versus low-calorie food pictures. Together, these findings indicate that loading the cognitive system moderates hedonic brain responses to high-calorie food pictures via interactions between NAcc and DLPFC. Our findings are consistent with the putative cognitive nature of food motivation. Implications for future research are discussed. Show less
The central theme of this dissertation is the (un)willingness to reward cooperation and punish non-cooperation. Whereas rewards and punishments can be effective means to enhance cooperation in... Show moreThe central theme of this dissertation is the (un)willingness to reward cooperation and punish non-cooperation. Whereas rewards and punishments can be effective means to enhance cooperation in social dilemmas, a prerequisite for any effect of sanctions is that people are willing to administer them. In the present work, I shed more light on this important – yet long neglected – topic. The aim is twofold: (1) identifying determinants of the use of sanctions in social dilemmas, and (2) testing the central proposition that people are not as willing to punish non-cooperative choice behavior as they are willing to reward cooperative choice behavior. The results of this dissertation show that the type of sanction people have at their disposal (Reward versus Punishment), the type of social dilemma people face (Public good dilemma versus Common resource dilemma), the extent of personal responsibility people have for the sanction (Individual responsibility versus Joint responsibility), and the timing of the sanctioning decision (Beforehand versus Afterwards) are important determinants of the (un)willingness to sanction in social dilemmas. These findings reveal that there are not only psychological processes at play that foster sanctioning, but also psychological processes that hamper sanctioning. Show less
Brand, F.A. van den; Nagelhout, G.E.; Winkens, B.; Evers, S.M.A.A.; Kotz, D.; Chavannes, N.H.; Schayck, C.P. van 2016
To promote cooperation, people often rely on the administration of sanctions. However, from previous research we know that those in control of sanctions are generally reluctant to punish non... Show moreTo promote cooperation, people often rely on the administration of sanctions. However, from previous research we know that those in control of sanctions are generally reluctant to punish non-cooperative choice behavior and prefer to reward cooperative choice behavior, which is consistent with the do-no-harm principle. We propose that people are reluctant to punish because they feel personally responsible for the harm done. As such, we argue and demonstrate that the relative preference for rewarding over punishing is more pronounced when people decide individually than jointly (Experiment 1 and 2). Moreover, we show that the effect of grouping individuals on the reluctance to punish is mediated by feelings of personal responsibility (Experiment 3). These findings corroborate our reasoning that the feeling of personal responsibility has a self-restraining impact on the willingness to punish those who impair others’ interests, but not on the willingness to reward those who serve others’ interests. Show less
Cohn, M.D.; Veltman, D.J.; Pape, L.E.; Lith, K. van; Vermeiren, R.R.J.M.; Brink, W. van den; ... ; Popma, A. 2015
