Johannes Haushofer

On the psychology of poverty

Poverty remains one of the most pressing problems facing the world; the mechanisms through which poverty arises and perpetuates itself, however, are not well understood. Here, we examine the evidence for the hypothesis that poverty may have particular psychological consequences that can lead to economic behaviors that make it difficult to escape poverty. The evidence indicates that poverty causes stress and negative affective states which in turn may lead to short-sighted and risk-averse decision-making, possibly by limiting attention and favoring habitual behaviors at the expense of goal-directed ones. Together, these relationships may constitute a feedback loop that contributes to the perpetuation of poverty. We conclude by pointing toward specific gaps in our knowledge and outlining poverty alleviation programs that this mechanism suggests.

Interpreting fMRI data: maps, modules and dimensions

Neuroimaging research over the past decade has revealed a detailed picture of the functional organization of the human brain. Here we focus on two fundamental questions that are raised by the detailed mapping of sensory and cognitive functions and illustrate these questions with findings from the object-vision pathway. First, are functionally specific regions that are located close together best understood as distinct cortical modules or as parts of a larger-scale cortical map? Second, what functional properties define each cortical map or module? We propose a model in which overlapping continuous maps of simple features give rise to discrete modules that are selective for complex stimuli.

Multivariate Patterns in Object-Selective Cortex Dissociate Perceptual and Physical Shape Similarity

Prior research has identified the lateral occipital complex (LOC) as a critical cortical region for the representation of object shape in humans. However, little is known about the nature of the representations contained in the LOC and their relationship to the perceptual experience of shape. We used human functional MRI to measure the physical, behavioral, and neural similarity between pairs of novel shapes to ask whether the representations of shape contained in subregions of the LOC more closely reflect the physical stimuli themselves, or the perceptual experience of those stimuli. Perceptual similarity measures for each pair of shapes were obtained from a psychophysical same-different task; physical similarity measures were based on stimulus parameters; and neural similarity measures were obtained from multivoxel pattern analysis methods applied to anterior LOC (pFs) and posterior LOC (LO). We found that the pattern of pairwise shape similarities in LO most closely matched physical shape similarities, whereas shape similarities in pFs most closely matched perceptual shape similarities. Further, shape representations were similar across participants in LO but highly variable across participants in pFs. Together, these findings indicate that activation patterns in subregions of object-selective cortex encode objects according to a hierarchy, with stimulus-based representations in posterior regions and subjective and observer-specific representations in anterior regions.

Both sides retaliate in the Israeli–Palestinian conflict

Ending violent international conflicts requires understanding the causal factors that perpetuate them. In the Israeli–Palestinian conflict, Israelis and Palestinians each tend to see themselves as victims, engaging in violence only in response to attacks initiated by a fundamentally and implacably violent foe bent on their destruction. Econometric techniques allow us to empirically test the degree to which violence on each side occurs in response to aggression by the other side. Prior studies using these methods have argued that Israel reacts strongly to attacks by Palestinians, whereas Palestinian violence is random (i.e., not predicted by prior Israeli attacks). Here we replicate prior findings that Israeli killings of Palestinians increase after Palestinian killings of Israelis, but crucially show further that when nonlethal forms of violence are considered, and when a larger dataset is used, Palestinian violence also reveals a pattern of retaliation: (i) the firing of Palestinian rockets increases sharply after Israelis kill Palestinians, and (ii) the probability (although not the number) of killings of Israelis by Palestinians increases after killings of Palestinians by Israel. These findings suggest that Israeli military actions against Palestinians lead to escalation rather than incapacitation. Further, they refute the view that Palestinians are uncontingently violent, showing instead that a significant proportion of Palestinian violence occurs in response to Israeli behavior. Well-established cognitive biases may lead participants on each side of the conflict to underappreciate the degree to which the other sides violence is retaliatory, and hence to systematically underestimate their own role in perpetuating the conflict.

No effects of psychosocial stress on intertemporal choice.

Intertemporal choices - involving decisions which trade off instant and delayed outcomes - are often made under stress. It remains unknown, however, whether and how stress affects intertemporal choice. We subjected 142 healthy male subjects to a laboratory stress or control protocol, and asked them to make a series of intertemporal choices either directly after stress, or 20 minutes later (resulting in four experimental groups). Based on theory and evidence from behavioral economics and cellular neuroscience, we predicted a bidirectional effect of stress on intertemporal choice, with increases in impatience or present bias immediately after stress, but decreases in present bias or impatience when subjects are tested 20 minutes later. However, our results show no effects of stress on intertemporal choice at either time point, and individual differences in stress reactivity (changes in stress hormone levels over time) are not related to individual differences in intertemporal choice. Together, we did not find support for the hypothesis that psychosocial laboratory stressors affect intertemporal choice.

For love or money: a common neural currency for social and monetary reward.

Two papers in the current issue of Neuron (Izuma et al. and Zink et al.) report that activity in specific regions of the brain, especially the striatum, reflects a common signal of reward in both the economic (e.g., money) and social (e.g., praise and status) domains.

Development of Behavioral Control and Associated vmPFC–DLPFC Connectivity Explains Children's Increased Resistance to Temptation in Intertemporal Choice

Human civilization is based on the successful pursuit of long-term goals, requiring the ability to forego immediate pleasure for the sake of larger future rewards. This ability improves with age, but the precise cognitive and neural mechanisms underlying its development remain elusive. The developmental changes could result either from younger children valuing immediate rewards more strongly or because older children become better at controlling their impulses. By implementing 2 tasks, a choice-independent valuation task and an intertemporal choice task, both behaviorally and using fMRI in twenty 6- to 13-year old children, we show developmental improvements in behavioral control to uniquely account for age-related changes in temporal discounting. We show further that overcoming temptation during childhood occurs as a function of an age-related increase in functional coupling between value signals in the ventromedial prefrontal cortex and brain regions dedicated to behavioral control, such as left dorsolateral prefrontal cortex during choice. These findings can help to devise measures that reduce the substantial costs of impatience to society.

Privileged Coding of Convex Shapes in Human Object-Selective Cortex

What is the neural code for object shape? Despite intensive research, the precise nature of object representations in high-level visual cortex remains elusive. Here we use functional magnetic resonance imaging (fMRI) to show that convex shapes are encoded in a privileged fashion by human lateral occipital complex (LOC), a region that has been implicated in object recognition. On each trial, two convex or two concave shapes that were either identical or different were presented sequentially. Critically, the convex and concave stimuli were the same except for a binocular disparity change that reversed the figure-ground assignment. The fMRI response in LOC for convex stimuli was higher for different than that for identical shape pairs, indicating sensitivity to differences in convex shape. However, when the same stimuli were seen as concave, the response for different and identical pairs was the same, indicating lower sensitivity to changes in concave shape than convex shape. This pattern was more pronounced in the anterior than that in the posterior portion of LOC. These results suggest that convex contours could be important elements in cortical object representations.

How do target predictability and precueing affect the production of express saccades in monkeys

The extent to which target predictability and precueing affect express saccade generation was determined in Rhesus monkeys. Target predictability, as manipulated by the probability with which targets appeared at various locations, had a strong influence on express saccade generation. Pre‐cueing the location of the appearance of an impending single target with an identical stimulus was effective in increasing express saccade generation when there was a gap of 50–150 ms between fixation spot termination and target onset. However, precueing was not effective when the gap time was set to 0 ms in the single target task, when several simultaneous targets appeared requiring a visual discrimination to be made using an oddity task, or when the precue was not identical to the target. These findings indicate that express saccades are facilitated by a restricted set of conditions that increase the predictability of target location and identity.

An examination of the variables that affect express saccade generation.

The frequency with which express saccades are generated under a variety of conditions in rhesus monkeys was examined. Increasing the gap time between fixation spot termination and target onset increased express saccade frequency but was progressively less effective in doing so as the number of target positions in the sample was increased. Express saccades were rarely produced when two targets were presented simultaneously and the choice of either of which was rewarded; a temporal asynchrony of only 17 ms between the targets reinstated express saccade generation. Express saccades continued to be generated when the vergence or pursuit systems was coactivated with the saccadic system.