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Ma K, Long Y, Huang C, Hommel B. Trust in virtual ingroup or outgroup members relies on perceived self-other overlap. Q J Exp Psychol (Hove) 2024; 77:1581-1594. [PMID: 37706293 DOI: 10.1177/17470218231203203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
Why do we trust each other? We carried out three experiments to test whether interpersonal trust depends on perceived self-other overlap. As previous studies suggest that enfacing (feeling ownership for, and include more into oneself of the face of) an avatar might make one trust this avatar more, we exposed participants to faces of ingroup and outgroup avatars that moved in synchrony or out of synchrony with the participant's own facial movements, and assessed the impact of synchrony on self-other overlap and trust measures. Experiment 1 used ingroup faces and successfully showed that synchrony (manipulated within-participants) increased self-other overlap and trust, which we assessed by means of the Trust Game and the Implicit Association Test (IAT). In Experiment 2, which used outgroup faces and a within-participants design, synchrony still increased scores in the Trust Game but the IAT was no longer affected. Experiment 3 replicated Experiment 2 but with synchrony varying between participants, which eliminated the synchrony effect in both trust measures. Importantly, Inclusion of Other in the Self (IOS) ratings were found to predict the IAT effect in synchronous conditions. Taken altogether, our findings suggest that interpersonal trust is mainly driven by perceived self-other overlap. Besides group identification, appearance, and voluntary movement, synchrony is just one of several sources contributing to perceived self-other overlap.
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Affiliation(s)
- Ke Ma
- Key Laboratory of Personality and Cognition, Faculty of Psychological Science, Southwest University, Chongqing, China
| | - Yan Long
- Key Laboratory of Personality and Cognition, Faculty of Psychological Science, Southwest University, Chongqing, China
| | - Chaojin Huang
- Key Laboratory of Personality and Cognition, Faculty of Psychological Science, Southwest University, Chongqing, China
| | - Bernhard Hommel
- Department of Psychology, Shandong Normal University, Jinan, China
- Faculty of Psychology and University Neuropsychology Center, Faculty of Medicine, Cognitive Neurophysiology, TU Dresden, Dresden, Germany
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2
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Pinjari OF, Jones GH, Vecera CM, Smith K, Barrera A, Machado-Vieira R. The Role of the Gut Microbiome in Bipolar Disorder and its Common Comorbidities. Front Neuroendocrinol 2023:101078. [PMID: 37220806 DOI: 10.1016/j.yfrne.2023.101078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 04/13/2023] [Accepted: 05/19/2023] [Indexed: 05/25/2023]
Abstract
Bipolar disorder is a decidedly heterogeneous and multifactorial disease, with significant psychosocial and medical disease burden. Much difficulty has been encountered in developing novel therapeutics and objective biomarkers for clinical use in this population. In that regard, gut-microbial homeostasis appears to modulate several key pathways relevant to a variety of psychiatric, metabolic, and inflammatory disorders. Microbial impact on immune, endocrine, endocannabinoid, kynurenine, and other pathways are discussed throughout this review. Emphasis is placed on this system's relevance to current pharmacology, diet, and comorbid illness in bipolar disorder. Despite the high level of optimism promoted in many reviews on this topic, substantial obstacles exist before any microbiome-related findings can provide meaningful clinical utility. Beyond a comprehensive overview of pathophysiology, this review hopes to highlight several key areas where progress is needed. As well, novel microbiome-associated suggestions are presented for future research.
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Affiliation(s)
- Omar F Pinjari
- Wayne Scott (J-IV) Unit of Correctional Managed Care, University of Texas Medical Branch.
| | - Gregory H Jones
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at Houston (UTHealth).
| | - Courtney M Vecera
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at Houston (UTHealth).
| | - Kacy Smith
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at Houston (UTHealth).
| | - Anita Barrera
- Department of Psychiatry and Behavioral Sciences, University of Texas Health Science Center at Houston (UTHealth).
| | - Rodrigo Machado-Vieira
- Wayne Scott (J-IV) Unit of Correctional Managed Care, University of Texas Medical Branch.
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3
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Typical diet and type of economy do not predict food-sharing behaviors in three Tanzanian societies. Appetite 2023; 182:106414. [PMID: 36503008 DOI: 10.1016/j.appet.2022.106414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 11/28/2022] [Accepted: 12/07/2022] [Indexed: 12/13/2022]
Abstract
Food sharing behavior is a widely observed phenomenon, and it draws attention of scholars interested in finding both proximate and ultimate explanations of such practices. In the current study, we focused on possible socio-economic and environmental food-sharing predictors: type of economy (i.e., immediate-return vs. delayed-return) and typical diet composition (i.e., proportion of proteins and carbohydrates in typical daily caloric intake). We investigated whether members of three societies from Tanzania (N = 177), namely hunter-gatherers (Hadza), pastoralists (Datoga), and agriculturalists (Iraqw) differ with regard to food-sharing patterns in the Dictator Game and reactions to violations of the food-sharing norms in the Ultimatum Game. We found that neither the type of economy nor the typical diet influenced our outcomes. The results indicated, however, that food sharing behavior was positively predicted by certain individual-level characteristics: people of higher strength and lower body fat shared more food, and women were more willing to share food than men.
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4
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The effects of probiotics on risk and time preferences. Sci Rep 2022; 12:12152. [PMID: 35840611 PMCID: PMC9287413 DOI: 10.1038/s41598-022-16251-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 07/07/2022] [Indexed: 11/08/2022] Open
Abstract
Animal models, human neuroimaging and lesion studies revealed that the gut microbiota can influence the interaction between the central and the enteric nervous systems via the gut–brain axis (GBA) and can affect brain regions linked to basic emotional and cognitive processes. The role of the gut microbiota in decision-making in healthy humans thus far remains largely unknown. Our study establishes a functional relationship between the gut microbiota and healthy humans’ decisions that involve risk and time. We conducted a between subjects’ placebo-controlled double-blinded design, with two groups and two sessions separated by 28 days, during which participants received daily doses of probiotics or a placebo. We investigated whether the prolonged and controlled intake of probiotics affects risk-taking behavior and intertemporal choices using incentivized economic tasks. We found a significant decrease in risk-taking behavior and an increase in future-oriented choices in the probiotics group as compared to the placebo group. These findings provide the first direct experimental evidence suggesting a potential functional role on the part of the microbiota-gut-brain axis in decision-making, creating a path for potential clinical applications and allowing for a better understanding of the underlying neural mechanisms of risk-taking behavior and intertemporal choices.
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5
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Zamoscik V, Schmidt SNL, Bravo R, Ugartemendia L, Plieger T, Rodríguez AB, Reuter M, Kirsch P. Tryptophan-enriched diet or 5-hydroxytryptophan supplementation given in a randomized controlled trial impacts social cognition on a neural and behavioral level. Sci Rep 2021; 11:21637. [PMID: 34737364 PMCID: PMC8568973 DOI: 10.1038/s41598-021-01164-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 10/22/2021] [Indexed: 02/08/2023] Open
Abstract
Understanding of emotions and intentions are key processes in social cognition at which serotonin is an important neuromodulator. Its precursor is the essential amino acid tryptophan (TRP). Reduced TRP availability leads to weaker impulse control ability and higher aggression, while TRP supplementation promotes confidence. In a double-blind placebo-controlled fMRI study with 77 healthy adults, we investigated the influence of a 4 week TRP enriched diet and an acute 5-hydroxytryptophan (5-HTP) intake on two social-cognitive tasks, a moral evaluation and an emotion recognition task. With 5-HTP, immoral behavior without negative consequences was rated as more reprehensible. Additionally, during story reading, activation in insula and supramarginal gyrus was increased after TRP intake. No significant effects of TRP on emotion recognition were identified for the whole sample. Importantly, emotion recognition ability decreased with age which was for positive emotions compensated by TRP. Since the supramarginal gyrus is associated with empathy, pain and related information integration results could be interpreted as reflecting stricter evaluation of negative behavior due to better integration of information. Improved recognition of positive emotions with TRP in older participants supports the use of a TRP-rich diet to compensate for age related decline in social-cognitive processes.
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Affiliation(s)
- V Zamoscik
- Department of Clinical Psychology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J 5, 68159, Mannheim, Germany. .,Department of Psychology, Laboratory of Neurogenetics, University of Bonn, Bonn, Germany.
| | - S N L Schmidt
- Research Group of Clinical Psychology, Department of Psychology, University of Konstanz, Konstanz, Germany
| | - R Bravo
- Chrononutrition Laboratory, Neuroimmunephysiology and Chrononutrition Research Group, Faculty of Science, University of Extremadura, Badajoz, Spain
| | - L Ugartemendia
- Chrononutrition Laboratory, Neuroimmunephysiology and Chrononutrition Research Group, Faculty of Science, University of Extremadura, Badajoz, Spain
| | - T Plieger
- Department of Psychology, Laboratory of Neurogenetics, University of Bonn, Bonn, Germany
| | - A B Rodríguez
- Chrononutrition Laboratory, Neuroimmunephysiology and Chrononutrition Research Group, Faculty of Science, University of Extremadura, Badajoz, Spain
| | - M Reuter
- Department of Psychology, Laboratory of Neurogenetics, University of Bonn, Bonn, Germany
| | - P Kirsch
- Department of Clinical Psychology, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, J 5, 68159, Mannheim, Germany
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6
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Bamberg C, Flasbeck V, Juckel G, Brüne M. Loudness Dependence of Auditory-evoked Potentials, a Marker of Central Serotonergic Activity, is Affected by Fasting and Selective Uptake of Food. Clin EEG Neurosci 2021; 52:391-399. [PMID: 33729043 DOI: 10.1177/15500594211000925] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Serotonin is an important neuromodulator involved in many physiological processes including mood and satiety. In the brain, serotonin is manufactured from tryptophan, as serotonin itself cannot cross the blood-brain barrier. Previous research has shown that blood-tryptophan levels increase upon ingestion of carbohydrates and decrease upon protein consumption. How this translates into serotonin availability is as yet under-researched. Therefore, we examined the effect of fasting versus consuming carbohydrates or protein on central serotonergic activity using a repeated-measures crossover design in a sample of 37 healthy men. The loudness dependence of auditory-evoked potentials (LDAEP) serves as a noninvasive method to study central serotonergic activity. Blood-glucose levels and mood changes were also monitored before and after the nutritional intervention. The intervention had a significant nutrition-specific effect on LDAEP and blood-glucose levels. A significant difference emerged between the fasting condition and satiety, with LDAEP being lower during satiety, irrespective of the type of food. Thus, this indicator of serotonergic activity increased after food consumption, which was further related to mood improvement. Moreover, the LDAEP differed between the 2 measurements only for the carbohydrate testing day, suggesting that LDAEP can be selectively modulated by the type of nutrition consumed. Our data further indicate a high intraindividual stability of LDAEP, as the electrophysiological signals were very similar in the fasting condition across the 2 testing days. Together, these findings demonstrate that the LDAEP can serve as a biological marker for central serotonergic activity, while at the same time being sensitive to nutritional changes.
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Affiliation(s)
| | - Vera Flasbeck
- 59970LWL University Hospital, Ruhr University Bochum, Germany
| | - Georg Juckel
- 59970LWL University Hospital, Ruhr University Bochum, Germany
| | - Martin Brüne
- 59970LWL University Hospital, Ruhr University Bochum, Germany
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7
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Bamberg CCL, Flasbeck V, Diop S, Brüne M. Ecology of cooperation: The influence of fasting and satiety on interpersonal trust. Soc Neurosci 2021; 16:134-144. [PMID: 33439787 DOI: 10.1080/17470919.2021.1876758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The willingness to cooperate in social interaction often depends on factors such as trustworthiness, reciprocity, and gender, but perhaps also on situational factors such as satiety. Here, we examined Trust Game performance before (fasting condition) and after ingestion of a high-caloric drink (satiety condition) of 37 psychologically healthy male subjects who played the game against individuals of both sexes differing in facial attractiveness. Participants invested significantly fewer money units (MUs) in the fasting condition compared to the satiated condition. Female opposing players received more MUs than males and attractive players more than less attractive ones. Time to arrive at a decision was shorter in the satiated condition than in the fasting condition. These findings indicate that satiety affects social cooperation and suggests that physical needs are prioritized over social cooperation.
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Affiliation(s)
- Christoph Claus Ludwig Bamberg
- LWL University Hospital, Department of Psychiatry, Psychotherapy and Preventive Medicine, Division of Social Neuropsychiatry and Evolutionary Medicine, Ruhr University Bochum, Bochum, Germany
| | - Vera Flasbeck
- LWL University Hospital, Department of Psychiatry, Psychotherapy and Preventive Medicine, Division of Social Neuropsychiatry and Evolutionary Medicine, Ruhr University Bochum, Bochum, Germany
| | - Shirin Diop
- LWL University Hospital, Department of Psychiatry, Psychotherapy and Preventive Medicine, Ruhr University Bochum, Bochum, Germany
| | - Martin Brüne
- LWL University Hospital, Department of Psychiatry, Psychotherapy and Preventive Medicine, Division of Social Neuropsychiatry and Evolutionary Medicine, Ruhr University Bochum, Bochum, Germany
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8
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Xu L, Becker B, Kendrick KM. Oxytocin Facilitates Social Learning by Promoting Conformity to Trusted Individuals. Front Neurosci 2019; 13:56. [PMID: 30787864 PMCID: PMC6372972 DOI: 10.3389/fnins.2019.00056] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 01/21/2019] [Indexed: 11/20/2022] Open
Abstract
There is considerable interest in the role of the neuropeptide oxytocin in promoting social cohesion both in terms of promoting specific social bonds and also more generally for increasing our willingness to trust others and/or to conform to their opinions. These latter findings may also be important in the context of a modulatory role for oxytocin in improving the efficacy of behavioral therapy in psychiatric disorders. However, the original landmark studies claiming an important role for oxytocin in enhancing trust in others, primarily using economic game strategies, have been questioned by subsequent meta-analytic approaches or failure to reproduce findings in different contexts. On the other hand, a growing number of studies have consistently reported that oxytocin promotes conformity to the views of groups of in-group individuals. Most recently we have found that oxytocin can increase acceptance of social advice given by individual experts without influencing their perceived trustworthiness per se, but that increased conformity in this context is associated with how much an expert is initially trusted and liked. Oxytocin can also enhance the impact of information given by experts by facilitating expectancy and placebo effects. Here we therefore propose that a key role for oxytocin is not in facilitating social trust per se but in conforming to, and learning from, trusted individuals who are either in-group members and/or perceived experts. The implications of this for social learning and use of oxytocin as an adjunct to behavioral therapy in psychiatric disorders are discussed. Interpersonal trust within social groups is of key importance for social interactions, bonds, cooperation and learning and trust between different groups can also help ensure a stable and peaceful co-existence as well as mutually beneficial co-operation and trade. Trust is generally considered to be critical for co-operation and reciprocity in social and economic interactions but importantly trust also involves risk of potential injury if misplaced or broken and we have a natural aversion to taking such risks (Hardin, 2002; Ostrom and Walker, 2003). Indeed, an important factor influencing our trust behavior is that we are strongly motivated to avoid others betraying our trust (Bohnet and Zeckhauser, 2004; Bohnet et al., 2008). Trust can potentially be influenced by our assessment of the level of risk that trusting others might have and also by increased sensitivity to physical and/or other cues for detecting trustworthiness. It is therefore of great importance to identify both behavioral and physiological factors which can act to enhance trust, particularly in situations where individuals have impaired trust and therefore find it hard to interact socially with others and learn from them and/or to benefit optimally from cognitive and behavioral therapeutic strategies.
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Affiliation(s)
| | | | - Keith M. Kendrick
- The Clinical Hospital of Chengdu Brain Science Institute, MOE Key Laboratory for NeuroInformation, University of Electronic Science and Technology of China, Chengdu, China
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9
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Wehebrink KS, Koelkebeck K, Piest S, de Dreu CKW, Kret ME. Pupil mimicry and trust - Implication for depression. J Psychiatr Res 2018; 97:70-76. [PMID: 29202275 DOI: 10.1016/j.jpsychires.2017.11.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 11/10/2017] [Accepted: 11/17/2017] [Indexed: 11/15/2022]
Abstract
Individuals suffering from depression often have difficulty trusting others. Previous research has shown a relationship between trust formation and pupil mimicry - the synchronization of pupil sizes between individuals. The current study therefore examined whether pupil mimicry is weaker in depressed individuals and an underlying factor of their low levels of trust. Forty-two patients with major depressive disorder (MDD) and 40 healthy control subjects played trust games with virtual partners. Images of these partners' eye regions were presented to participants before they had to make a monetary investment decision. Partners' pupils either dilated, constricted, or remained static over the course of 4-s interactions. During the task, participants' pupil sizes were recorded with eye-tracking equipment to assess mimicry. The results confirm that patients with MDD were somewhat less trusting than controls and used another's pupillary cues differently when deciding to trust. Specifically, whereas healthy controls trusted partners with dilating pupils more than partners with constricting pupils, patients with MDD particularly trusted partners whose pupils changed in size less, regardless of whether partners' pupils were dilating or constricting. This difference in investment behavior was unrelated to differences in pupil mimicry, which was equally apparent in both groups and fostered trust to the same extent. Whereas lower levels of trust observed in patients with MDD could not be explained by differences in pupil mimicry, our data show that pupil dilation mimicry might help people to trust. These findings provide further evidence for the important role of pupil size and pupil mimicry in interpersonal trust formation and shed light on the pathophysiology of clinically low trust in patients with MDD.
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Affiliation(s)
- Katharina S Wehebrink
- Leiden University, Cognitive Psychology Unit, Wassenaarseweg 52, 2333 AK Leiden, The Netherlands; Leiden Institute for Brain and Cognition (LIBC), 2300 UC Leiden, The Netherlands; University of Muenster, School of Medicine, Department of Psychiatry and Psychotherapy, Albert-Schweitzer-Campus 1, A9, 48149 Muenster, Germany
| | - Katja Koelkebeck
- University of Muenster, School of Medicine, Department of Psychiatry and Psychotherapy, Albert-Schweitzer-Campus 1, A9, 48149 Muenster, Germany
| | - Simon Piest
- Martin-Luther-University Halle-Wittenberg, School of Law and Economics, Große Steinstrasse 73, 06108 Halle (Saale), Germany
| | - Carsten K W de Dreu
- Leiden University, Department of Social Psychology, Wassenaarseweg 52, 2333 AK Leiden, The Netherlands; Leiden Institute for Brain and Cognition (LIBC), 2300 UC Leiden, The Netherlands
| | - Mariska E Kret
- Leiden University, Cognitive Psychology Unit, Wassenaarseweg 52, 2333 AK Leiden, The Netherlands; Leiden Institute for Brain and Cognition (LIBC), 2300 UC Leiden, The Netherlands.
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10
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Abstract
Food intake is essential for maintaining homeostasis, which is necessary for survival in all species. However, food intake also impacts multiple biochemical processes that influence our behavior. Here, we investigate the causal relationship between macronutrient composition, its bodily biochemical impact, and a modulation of human social decision making. Across two studies, we show that breakfasts with different macronutrient compositions modulated human social behavior. Breakfasts with a high-carbohydrate/protein ratio increased social punishment behavior in response to norm violations compared with that in response to a low carbohydrate/protein meal. We show that these macronutrient-induced behavioral changes in social decision making are causally related to a lowering of plasma tyrosine levels. The findings indicate that, in a limited sense, "we are what we eat" and provide a perspective on a nutrition-driven modulation of cognition. The findings have implications for education, economics, and public policy, and emphasize that the importance of a balanced diet may extend beyond the mere physical benefits of adequate nutrition.
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11
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The role of serotonin in personality inference: tryptophan depletion impairs the identification of neuroticism in the face. Psychopharmacology (Berl) 2017; 234:2139-2147. [PMID: 28488040 PMCID: PMC5486943 DOI: 10.1007/s00213-017-4619-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 03/27/2017] [Indexed: 01/31/2023]
Abstract
Serotonergic mechanisms mediate the expression of personality traits (such as impulsivity, aggression and anxiety) that are linked to vulnerability to psychological illnesses, and modulate the identification of emotional expressions in the face as well as learning about broader classes of appetitive and aversive signals. Faces with neutral expressions signal a variety of socially relevant information, such that inferences about the big five personality traits, including Neuroticism, Extraversion and Agreeableness, can be accurately made on the basis of emotionally neutral facial photographs. Given the close link between Neuroticism and psychological distress, we investigated the effects of diminished central serotonin activity (achieved by tryptophan depletion) upon the accuracy of 52 healthy (non-clinical) adults' discriminations of personality from facial characteristics. All participants were able to discriminate reliably four of the big five traits. However, the tryptophan-depleted participants were specifically less accurate in discriminating Neuroticism than the matched non-depleted participants. These data suggest that central serotonin activity modulates the identification of not only negative facial emotional expression but also a broader class of signals about personality characteristics linked to psychological distress.
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12
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Lippelt DP, van der Kint S, van Herk K, Naber M. No Acute Effects of Choline Bitartrate Food Supplements on Memory in Healthy, Young, Human Adults. PLoS One 2016; 11:e0157714. [PMID: 27341028 PMCID: PMC4920398 DOI: 10.1371/journal.pone.0157714] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 06/05/2016] [Indexed: 01/24/2023] Open
Abstract
Choline is a dietary component and precursor of acetylcholine, a crucial neurotransmitter for memory-related brain functions. In two double-blind, placebo-controlled cross-over experiments, we investigated whether the food supplement choline bitartrate improved declarative memory and working memory in healthy, young students one to two hours after supplementation. In experiment 1, 28 participants performed a visuospatial working memory task. In experiment 2, 26 participants performed a declarative picture memorization task. In experiment 3, 40 participants performed a verbal working memory task in addition to the visuospatial working memory and declarative picture task. All tasks were conducted approximately 60 minutes after the ingestion of 2.0–2.5g of either choline bitartrate or placebo. We found that choline did not significantly enhance memory performance during any of the tasks. The null hypothesis that choline does not improve memory performance as compared to placebo was strongly supported by Bayesian statistics. These results are in contrast with animal studies suggesting that choline supplementation boosts memory performance and learning. We conclude that choline likely has no acute effects on cholinergic memory functions in healthy human participants.
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Affiliation(s)
- D P Lippelt
- Cognitive Psychology, Leiden University, Wassenaarseweg 52, Leiden, 2333AK, The Netherlands
| | - S van der Kint
- Cognitive Psychology, Leiden University, Wassenaarseweg 52, Leiden, 2333AK, The Netherlands
| | - K van Herk
- Cognitive Psychology, Leiden University, Wassenaarseweg 52, Leiden, 2333AK, The Netherlands
| | - M Naber
- Cognitive Psychology, Leiden University, Wassenaarseweg 52, Leiden, 2333AK, The Netherlands.,Leiden Institute of Brain and Cognition, LUMC, Leiden, 2300 RC, The Netherlands.,Experimental Psychology, Utrecht University, Heidelberglaan 2, Utrecht, 3584CS, The Netherlands
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13
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Steenbergen L, Jongkees BJ, Sellaro R, Colzato LS. Tryptophan supplementation modulates social behavior: A review. Neurosci Biobehav Rev 2016; 64:346-58. [DOI: 10.1016/j.neubiorev.2016.02.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 02/22/2016] [Accepted: 02/23/2016] [Indexed: 01/09/2023]
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14
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Colzato LS, Sellaro R, van den Wildenberg WPM, Hommel B. tDCS of Medial Prefrontal Cortex Does Not Enhance Interpersonal Trust. J PSYCHOPHYSIOL 2015. [DOI: 10.1027/0269-8803/a000144] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Abstract. Interpersonal trust is an essential ingredient of many social relationships. Previous research has suggested that the medial Prefrontal Cortex (mPFC) may be a critical component in mediating the degree to which people trust others. Here we assessed the role of the mPFC in modulating interpersonal trust by means of transcranial direct current stimulation (tDCS). Participants (n = 60) were randomly and equally assigned to receive anodal, cathodal, or sham stimulation while performing the Trust Game, an index of interpersonal trust that assesses the money units one participant (the trustor) transfers to another (the trustee). Results showed that neither anodal stimulation (brain stimulation that increases cortical excitability of the area being stimulated) nor cathodal stimulation (brain stimulation that decreases cortical excitability) affected the degree of interpersonal trust as compared to sham stimulation. We conclude that noninvasive electrical stimulation over the mPFC does not modulate the degree to which people trust others.
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Affiliation(s)
- Lorenza S. Colzato
- Cognitive Psychology Unit & Leiden Institute for Brain and Cognition, Leiden University, Leiden, The Netherlands
| | - Roberta Sellaro
- Cognitive Psychology Unit & Leiden Institute for Brain and Cognition, Leiden University, Leiden, The Netherlands
| | - Wery P. M. van den Wildenberg
- Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Brain & Cognition (ABC), University of Amsterdam, Amsterdam, The Netherlands
| | - Bernhard Hommel
- Cognitive Psychology Unit & Leiden Institute for Brain and Cognition, Leiden University, Leiden, The Netherlands
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15
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Crockett MJ, Cools R. Serotonin and aversive processing in affective and social decision-making. Curr Opin Behav Sci 2015. [DOI: 10.1016/j.cobeha.2015.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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16
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Hommel B, Colzato LS. Interpersonal trust: an event-based account. Front Psychol 2015; 6:1399. [PMID: 26441774 PMCID: PMC4584930 DOI: 10.3389/fpsyg.2015.01399] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 09/02/2015] [Indexed: 11/29/2022] Open
Affiliation(s)
- Bernhard Hommel
- Cognitive Psychology Unit and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
| | - Lorenza S Colzato
- Cognitive Psychology Unit and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
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17
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Naber M, Hommel B, Colzato LS. Improved human visuomotor performance and pupil constriction after choline supplementation in a placebo-controlled double-blind study. Sci Rep 2015; 5:13188. [PMID: 26271904 PMCID: PMC4536529 DOI: 10.1038/srep13188] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 07/09/2015] [Indexed: 12/05/2022] Open
Abstract
Only few nutrients are known to enhance cognition. Here we explore whether visuomotor performance can be improved through the intake of the nutrient choline, an essential chemical compound in a vertebrate's diet. Choline is abundant in for example eggs and shrimps and many animal studies suggest that it serves as a cognitive enhancer. As choline is important for the communication between motor neurons and the control of skeletal muscles, we assumed that choline supplementation may have positive effects on action coordination in humans. A group of twenty-eight individuals ingested two grams of choline bitartrate or a placebo in two separate sessions. Seventy minutes post ingestion, participants performed a visuomotor aiming task in which they had to rapidly hit the centers of targets. Results showed that participants hit targets more centrally after choline supplementation. Pupil size (a cognition-sensitive biomarker) also significantly decreased after choline intake and correlated positively with the hit distance to the targets and the number of target misses, and negatively with reaction times. These findings point to a choline-induced bias towards action precision in the trade-off between speed and accuracy. The changes in pupil size suggest that choline uptake alters cholinergic functions in the nervous system.
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Affiliation(s)
- Marnix Naber
- Leiden University, Cognitive Psychology, Wassenaarseweg 52, Leiden, 2333 AK, The Netherlands
- Leiden Institute for Brain and Cognition, Leiden University Medical Center, P.O. Box 9600, Leiden, 2300 RC, The Netherlands
| | - Bernhard Hommel
- Leiden University, Cognitive Psychology, Wassenaarseweg 52, Leiden, 2333 AK, The Netherlands
- Leiden Institute for Brain and Cognition, Leiden University Medical Center, P.O. Box 9600, Leiden, 2300 RC, The Netherlands
| | - Lorenza S. Colzato
- Leiden University, Cognitive Psychology, Wassenaarseweg 52, Leiden, 2333 AK, The Netherlands
- Leiden Institute for Brain and Cognition, Leiden University Medical Center, P.O. Box 9600, Leiden, 2300 RC, The Netherlands
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18
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Sellaro R, van Dijk WW, Paccani CR, Hommel B, Colzato LS. A question of scent: lavender aroma promotes interpersonal trust. Front Psychol 2015; 5:1486. [PMID: 25628577 PMCID: PMC4290497 DOI: 10.3389/fpsyg.2014.01486] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 12/02/2014] [Indexed: 12/04/2022] Open
Abstract
A previous study has shown that the degree of trust into others might be biased by inducing either a more “inclusive” or a more “exclusive” cognitive-control mode. Here, we investigated whether the degree of interpersonal trust can be biased by environmental factors, such as odors, that are likely to impact cognitive-control states. Arousing olfactory fragrances (e.g., peppermint) are supposed to induce a more exclusive, and calming olfactory fragrances (e.g., lavender) a more inclusive state. Participants performed the Trust Game, which provides an index of interpersonal trust by assessing the money units one participant (the trustor) transfers to another participant (the trustee), while being exposed to either peppermint or lavender aroma. All participants played the role of trustor. As expected, participants transferred significantly more money to the alleged trustee in the lavender as compared to the peppermint and control (no aroma) conditions. This observation might have various serious implications for a broad range of situations in which interpersonal trust is an essential element, such as cooperation (e.g., mixed-motives situations), bargaining and negotiation, consumer behavior, and group performance.
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Affiliation(s)
- Roberta Sellaro
- Cognitive Psychology Unit and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
| | - Wilco W van Dijk
- Cognitive Psychology Unit and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
| | - Claudia Rossi Paccani
- Cognitive Psychology Unit and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
| | - Bernhard Hommel
- Cognitive Psychology Unit and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
| | - Lorenza S Colzato
- Cognitive Psychology Unit and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
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Steenbergen L, Sellaro R, Hommel B, Colzato LS. Tyrosine promotes cognitive flexibility: evidence from proactive vs. reactive control during task switching performance. Neuropsychologia 2015; 69:50-5. [PMID: 25598314 DOI: 10.1016/j.neuropsychologia.2015.01.022] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 01/12/2015] [Accepted: 01/15/2015] [Indexed: 11/25/2022]
Abstract
Tyrosine (TYR), an amino acid found in various foods, has been shown to increase dopamine (DA) levels in the brain. Recent studies have provided evidence that TYR supplementation can improve facets of cognitive control in situations with high cognitive demands. Here we investigated whether TYR promotes cognitive flexibility, a cognitive-control function that is assumed to be modulated by DA. We tested the effect of TYR on proactive vs. reactive control during task switching performance, which provides a relatively well-established diagnostic of cognitive flexibility. In a double-blind, randomized, placebo-controlled design, 22 healthy adults performed in a task-switching paradigm. Compared to a neutral placebo, TYR promoted cognitive flexibility (i.e. reduced switching costs). This finding supports the idea that TYR can facilitate cognitive flexibility by repleting cognitive resources.
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Affiliation(s)
- Laura Steenbergen
- Institute for Psychological Research, Leiden University, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, 2333 AK Leiden, The Netherlands.
| | - Roberta Sellaro
- Institute for Psychological Research, Leiden University, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, 2333 AK Leiden, The Netherlands
| | - Bernhard Hommel
- Institute for Psychological Research, Leiden University, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, 2333 AK Leiden, The Netherlands
| | - Lorenza S Colzato
- Institute for Psychological Research, Leiden University, The Netherlands; Leiden Institute for Brain and Cognition, Leiden University, Leiden, 2333 AK Leiden, The Netherlands
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20
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Steenbergen L, Sellaro R, Colzato LS. Tryptophan promotes charitable donating. Front Psychol 2014; 5:1451. [PMID: 25566132 PMCID: PMC4268492 DOI: 10.3389/fpsyg.2014.01451] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 11/27/2014] [Indexed: 11/13/2022] Open
Abstract
The link between serotonin (5-HT) and one of the most important elements of prosocial behavior, charity, has remained largely uninvestigated. In the present study, we tested whether charitable donating can be promoted by administering the food supplement L-Tryptophan (TRP), the biochemical precursor of 5-HT. Participants were compared with respect to the amount of money they donated when given the opportunity to make a charitable donation. As expected, compared to a neutral placebo, TRP appears to increase the participants’ willingness to donate money to a charity. This result supports the idea that the food we eat may act as a cognitive enhancer modulating the way we think and perceive the world and others.
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Affiliation(s)
- Laura Steenbergen
- Cognitive Psychology Unit, Institute for Psychological Research and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
| | - Roberta Sellaro
- Cognitive Psychology Unit, Institute for Psychological Research and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
| | - Lorenza S Colzato
- Cognitive Psychology Unit, Institute for Psychological Research and Leiden Institute for Brain and Cognition, Leiden University Leiden, Netherlands
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Sellaro R, Hommel B, de Kwaadsteniet EW, van de Groep S, Colzato LS. Increasing interpersonal trust through divergent thinking. Front Psychol 2014; 5:561. [PMID: 24936194 PMCID: PMC4047710 DOI: 10.3389/fpsyg.2014.00561] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 05/20/2014] [Indexed: 12/31/2022] Open
Abstract
Interpersonal trust is an essential ingredient of many social relationships but how stable is it actually, and how is it controlled? There is evidence that the degree of trust into others might be rather volatile and can be affected by manipulations like drawing attention to personal interdependence or independence. Here we investigated whether the degree of interpersonal trust can be biased by inducing either a more integrative or a more focused/exclusive cognitive control mode by means of a creativity task requiring divergent or convergent thinking, respectively. Participants then performed the trust game, which provides an index of interpersonal trust by assessing the money units one participant (the trustor) transfers to another (the trustee). As expected, trustors transferred significantly more money to trustees after engaging in divergent thinking as compared to convergent thinking. This observation provides support for the idea that interpersonal trust is controlled by domain-general (i.e., not socially dedicated) cognitive states.
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Affiliation(s)
| | | | | | | | - Lorenza S. Colzato
- Institute for Psychological Research and Leiden Institute for Brain and Cognition, Leiden UniversityLeiden, Netherlands
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