Human memory is strikingly susceptible to social influences, yet we know little about the underlying mechanisms. We examined how socially induced memory errors are generated in the brain by studying the memory of individuals exposed to recollections of others. Participants exhibited a strong tendency to conform to erroneous recollections of the group, producing both long-lasting and temporary errors, even when their initial memory was strong and accurate. Functional brain imaging revealed that social influence modified the neuronal representation of memory. Specifically, a particular brain signature of enhanced amygdala activity and enhanced amygdala-hippocampus connectivity predicted long-lasting, but not temporary memory alterations. Our findings reveal how social manipulation can alter memory and extend the known functions of the amygdala to encompass socially-mediated memory distortions.Our memories are often inaccurate. Ubiquitous sources of false recollection are social pressure and interpersonal influence (1-4). This phenomenon, dubbed "memory conformity" (4), is encountered in a variety of contexts, including social interactions, mass media exposure and eyewitness testimony. In such settings an individual may change veridical recollections of past events to match a false account provided by others (1-6). Although these social influences on memory have been extensively demonstrated (1-5), the underlying neurobiology of this process is unknown.Conformity may present in two forms which initially convey similar explicit behavior but are fundamentally different (7-8). In one type, known as private conformity, an individual's recollection may genuinely be altered by social influence, resulting in long lasting, persistent memory errors (1,4-5,7). In such circumstances, even when social influence is removed, the individuals will persist in claiming an erroneous memory as part of their own experience (7,9). Private conformity could hence be considered a bona fide memory change. In the second type, known as 'public conformity', individuals may choose to outwardly comply, providing an account that fits that of others, but inwardly maintain certitude in their own original memory. Public conformity can be dispelled when the veracity of the socially transferred information abates (7,(10)(11). Thus, errors induced by public conformity are transient (7,9) and appear to represent a change in behavior in the absence of lasting alterations to a memory engram.Although private and public memory conformity are often behaviorally indistinguishable, they reflect different cognitive processes (7)(8) Our experimental protocol included four phases spanning a 2 week period (Fig. 1A). Thirty adult participants (12 females, age 28.6 ± 0.8, mean ± SEM) viewed an eyewitness-style documentary on a large screen in groups of five. Three days after viewing, participants returned to the lab individually and completed a memory test (Test 1). Test 1 served to assess the participants' baseline accuracy and confidence before the manipul...

We here review existing evidence for majority influences in children under the age of ten years and comparable studies with animals ranging from fish to apes. Throughout the review, we structure the discussion surrounding majority influences by differentiating the behaviour of individuals in the presence of a majority and the underlying mechanisms and motivations. Most of the relevant research to date in both developmental psychology and comparative psychology has focused on the behavioural outcomes, where a multitude of mechanisms could be at play. We further propose that interpreting cross-species differences in behavioural patterns is difficult without considering the psychology of the individual. Some attempts at this have been made both in developmental psychology and comparative psychology. We propose that physiological measures should be used to subsidize behavioural studies in an attempt to understand the composition of mechanisms and motivations underlying majority influence. We synthesize the relevant evidence on human brain function in order to provide a framework for future investigation in this area. In addition to streamlining future research efforts, we aim to create a conceptual platform for productive exchanges across the related disciplines of developmental and comparative psychology.

No abstract

Humans are strongly influenced by their environment, a dependence that can lead to errors in judgment. Although a rich literature describes how people are influenced by others, little is known regarding the factors that predict subsequent rectification of misleading influence. Using a mediation model in combination with brain imaging, we propose a model for the correction of misinformation. Specifically, our data suggest that amygdala modulation of hippocampal mnemonic representations, during the time of misleading social influence, is associated with reduced subsequent anterior-lateral prefrontal cortex activity that reflects correction. These findings illuminate the process by which erroneous beliefs are, or fail to be, rectified and highlight how past influence constrains subsequent correction.

Decisions as diverse as committing soldiers to the battlefield or picking a school for your child share a basic attribute: assuming responsibility for the outcome of others. This responsibility is inherent in the roles of prime ministers and generals, as well as in the more quotidian roles of firmmanagers, schoolteachers, and parents. Here we identify the underlying behavioral, computational, and neurobiologicalmechanisms that determine the choice to assume responsibility over others. Leaders must take responsibility for others and affect the well-being of individuals, organizations, and nations. We identify the effects of responsibility on leaders' choices at the behavioral and neurobiological level and document the widespread existence of responsibility aversion, i.e., a reduced willingness to make decisions if the welfare of others is at stake. In mechanistic terms, basic preferences towards risk, losses and ambiguity do not explain responsibility aversion which, instead, is driven by a second-order cognitive process reflecting an increased demand for certainty about the best choice when others' welfare is affected. Finally, models estimating levels of information flow between brain regions processing separate choice components, provide the first step in understanding the neurobiological basis of individual variability in responsibility aversion and leadership scores. We identify and characterize the computations and neural mechanisms underlying choices to lead. This file includes:Hyperlinked Table of Contents Materials and Methods Supplementary ResultsFigs. S1 to S8 Tables S1 to S7 References and notes Appendix S1Appendix S22 Participants and sample size determination.We conducted the experiment with two separate samples of participants -marked throughout the manuscript as original and fMRI replication groups. The difference between the groups was that the latter performed the delegation task in the MRI scanner. Previous laboratory experiments on individual versus group decision making have typically used between 30-50 participants (37-39).Power calculations (40) based on the aforementioned studies average effect sizes suggested a stopping criterion of 40 participants as a reasonable estimate to ensure a statistical power of 0.8 (with an alpha level of 0.05). We thus recruited 40 participants for the original group (21 females; age 25.7 ± 0.66 standard error of the mean). In the fMRI replication group, we added, a priori, four additional participants (constituting one unit of participants, see below, resulting in 44 participants; 25 females; age 23.5 ± 0.43). This was done in anticipation of some minor data loss due to issues such as excessive head movement in the scanner, and because the minimum experimental session size could not be under eight participants (see task design below). The data for three participants were not fully collected (two participants failed the test quiz assessing comprehension of the instructions and one participant did not show up for the second stage), resulting in a fi...