New paper on honesty and deception

New paper offering a signaling perspective on studying the neural substrates of honesty and deception.

Jenkins, Adrianna, Lusha Zhu, and Ming Hsu. “Cognitive neuroscience of honesty and deception: A signaling framework.” Current Opinions in Behavioral Sciences.

New paper on culture and genes

Shinobu Kitayama, Tony King, Israel Liberzon, and I just had a review paper on the interaction between genes and culture accepted1. I'm not a cultural psychology researcher, and never thought about it much prior to talking to Shinobu. His paper on the relationship between rice and wheat cultivation on the one hand, and culture on the other, really changed how I think about the role of biology and culture.

Briefly, northern China largely relies on wheat-based cultivation, whereas souther China is largely rice-based. There are also pretty profound cultural differences. But up until now nobody bothered to quantitatively link the two and provide some rationale for why they might be connected. You'll have to read their paper for the full story, but for me it makes an incredible amount of sense, and also explains some of the regional stereotypes that every Chinese speaker would know by heart.

The other benefit of thinking about behavioral consequences of culture is that it allows for a much more mechanistic conceptualization of the effects of genes on culture, which is what our paper discusses. Below is one of the figures from the paper that tries to capture why social scientists interested in culture should care about biology, and why biological researchers should care about culture. Obviously this is incomplete and missing many important details, but given that culture is typically thought of as a nuisance variable in genetic and biological research, this is already an important step forward.

1 Kitayama, Shinobu, Anthony King, Ming Hsu, and Israel Liberzon. “Dopamine-System Genes and Cultural Acquisition: The Norm Sensitivity Hypothesis.” Current Opinion in Psychology.

New paper on neuroeconomics and neurology

My collaborators at UCSF's Memory and Aging Center just had a paper accepted in Brain, where we applied neuroeconomic tools to characterize behavioral deficits in frontotemporal dementia patients. Behavioral and social dysfunctions are some of the most difficult to capture quantitatively, even though they are often the most visible symptoms to family and loved ones. Hopefully we will be able to finally make some inroads given all that we have learned in neuroeconomics in the past decade.

Chiong, Winston, Kristie Wood, Alexander Beagle, Ming Hsu, Andrew Kayser, Bruce Miller, and Joel Kramer. “Neuroeconomic dissociation of semantic dementia and behavioral variant frontotemporal dementia.” Brain.

New paper on decoding brand personality

Congratulations to Yuping Chen, whose paper has been conditionally accepted at Journal of Marketing Research! The study used fMRI and model-based MVPA methods to decode consumers' thoughts to well-known commercial brands.

From “Where” to “What”: Distributed Representations of Brand Associations in the Human Brain

Yuping Chen, Leif Nelson, and Ming Hsu

Considerable attention has been given to the notion that there exists a set of human-like characteristics associated with brands, referred to as brand personality. Here we combine newly available machine learning techniques with functional neuroimaging data to characterize the set of processes that give rise to these associations. We show that brand personality traits can be captured by the weighted activity across a widely distributed set of brain regions previously implicated in reasoning, imagery, and affective processing. That is, as opposed to being constructed via reflective processes, brand personality traits appear to exist a priori inside the minds of consumers, such that we were able to predict what brand a person is thinking about based solely on the relationship between brand personality associations and brain activity. These findings represent an important advance in the application of neuroscientific methods to consumer research, moving from work focused on cataloguing brain regions associated with marketing stimuli to testing and refining mental constructs central to theories of consumer behavior. 

New article on causal effect of dopaminergic drug on inequity aversion

Congratulations to Ignacio, our paper on the causal involvement of prefrontal dopamine has just been accepted at Current Biology!

Egalitarian Behavior in Humans

Ignacio Saez, Lusha Zhu, Eric Set, Andrew Kayser, and Ming Hsu

Egalitarian motives form a powerful force in promoting prosocial behavior and enabling large-scale cooperation in the human species. At the neural level, there is substantial, albeit correlational, evidence suggesting a link between dopamine and such behavior. However, important questions remain about the specific role of dopamine in setting or modulating behavioral sensitivity to prosocial concerns. Here, using a combination of pharmacological tools and economic games, we provide critical evidence for a causal involvement of dopamine in human egalitarian tendencies. Specifically, using the brain penetrant catechol-O-methyl transferase (COMT) inhibitor tolcapone, we investigated the causal relationship between dopaminergic mechanisms and two prosocial concerns at the core of a number of widely used economic games: (1) the extent to which individuals directly value the material payoffs of others, i.e., generosity, and (2) the extent to which they are averse to differences between their own payoffs and those of others, i.e., inequity. We found that dopaminergic augmentation via COMT inhibition increased egalitarian tendencies in participants who played an extended version of the dictator game. Strikingly, computational modeling of choice behavior revealed that tolcapone exerted selective effects on inequity aversion, and not on other computational components such as the extent to which individuals directly value the material payoffs of others. Together, these data shed light on the causal relationship between neurochemical systems and human prosocial behavior and have potential implications for our understanding of the complex array of social impairments accompanying neuropsychiatric disorders involving dopaminergic dysregulation.

New article on causal involvement of DLPFC in honesty

Our paper on the causal involvement of DLPFC in honesty has just been accepted at Nature Neuroscience! This will hopefully be one in a long line of papers by us and others applying signaling games to the study of honesty and deception.

Damage to dorsolateral prefrontal cortex affects tradeoffs between honesty and self-interest

Lusha Zhu, Adrianna C Jenkins, Eric Set, Donatella Scabini, Robert T Knight, Pearl H Chiu, Brooks King-Casas, and Ming Hsu

Substantial correlational evidence suggests that prefrontal regions are critical to honest and dishonest behavior, but causal evidence specifying the nature of this involvement remains absent. We found that lesions of the human dorsolateral prefrontal cortex (DLPFC) decreased the effect of honesty concerns on behavior in economic games that pit honesty motives against self-interest, but did not affect decisions when honesty concerns were absent. These results point to a causal role for DLPFC in honest behavior.

New article on dopamine genes and strategic learning

Eric Set's paper on dopamine genes and strategic learning has just been accepted at PNAS. This has been an immense amount of work both conceptually thinking about how to characterize genetic effects on behavior in the context of the computational principles we have learned over the past decade, as well as statistically dealing with them in a tractable manner. I particularly liked the comments of one of our reviewers:

Set and colleagues present an impressive study combining sophisticated modeling of strategic behavior and a sophisticated genetic modeling approach.

Congratulations Eric! [PNAS Link]

Dissociable contribution of prefrontal and striatal dopaminergic genes to learning in economic games

Eric Set, Ignacio Saez, Lusha Zhu, Daniel E. Houser, Noah Myung, Songfa Zhong, Richard P. Ebsteing, Soo Hong Chew, and Ming Hsu

Game theory describes strategic interactions where success of players’ actions depends on those of coplayers. In humans, substantial progress has been made at the neural level in characteriz ing the dopaminergic and frontostriatal mechanisms mediating such behavior. Here we combined computational modeling of strategic learning with a pathway approach to characterize association of strategic behavior with variations in the dopamine pathway. Specifically, using gene-set analysis, we systematically examined contribution of different dopamine genes to variation in a multistrategy competitive game captured by (i) the degree players anticipate and respond to actions of others (belief learning) and (ii) the speed with which such adaptations take place (learning rate). We found that variation in genes that primarily regulate prefrontal dopamine clearance—catechol-O-methyl transferase (COMT) and two isoforms of monoamine oxidase—modulated degree of belief learning across individuals. In contrast, we did not find significant association for other genes in the dopamine pathway. Furthermore, variation in genes that primarily regulate striatal dopamine function—dopamine transporter and D2 receptors—was significantly associated with the learning rate. We found that this was also the case with COMT, but not for other dopaminergic genes. Together, these findings highlight dissociable roles of frontostriatal systems in strategic learning and support the notion that genetic variation, organized along specific pathways, forms an important source of variation in complex phenotypes such as strategic behavior.

New Article on Aging and Games

New paper coming out on changes in decision-making across the lifespan. Lifespan differences is an area of interest since my time at Illinois, where there were a number of world-class researchers on age-related changes in memory, executive function, and emotion. Surprisingly, despite the immense knowledge in these area, we still know very little about social functioning, particularly about social decision-making. I think this is changing, as in addition to ours, there have been several recently, including this fMRI paper on the aging and Ultimatum Game by Alan Sanfey.

Zhu, Lusha, Daniel Walsh, and Ming Hsu. Neuroeconomic Measures of Social Decision-Making Across the Lifespan. Frontiers in Neuro​science, 6:128. doi: 10.3389/fnins.2012.00128.

PNAS Article on Strategic Learning

New paper Dissociable neural representations of reinforcement and belief prediction errors underlie strategic learning coming out in PNAS. First paper from Lusha Zhu’s Ph.D. thesis!

Distributive Justice Paper Out

Our paper “The Right and the Good: Distributive Justice and Neural Encoding of Equity and Efficiency” is out ahead of print at Science. The paper version is scheduled to print on May 26. BTW, for Chinese press releases, it would’ve been cool if they put 许明 instead of Ming Hsu. It’s somehow jarring to see sentences like “Ming Hsu及其同僚应用功能性核磁共振”. But of course nobody asked me.