Foundations of Cooperation in Young Children

Observations and experiments show that human adults preferentially share resources with close relations, with people who have shared with them (reciprocity), and with people who have shared with others (indirect reciprocity). These tendencies are consistent with evolutionary theory but could also reflect the shaping effects of experience or instruction in complex, cooperative and competitive societies. Here we report evidence for these three tendencies in 3.5 year old children, despite their limited experience with complex cooperative networks. Three pillars of mature cooperative behavior therefore appear to have roots extending deep into human development.Psycholog

Subharmonics and Auditory Nerve Tuning Curves in Gerbil

In the literature, an auditory nerve tuning curve obtained from single unit recording typically has a tail and a tip. Responses beyond the tip in the well supra-CF frequency region had never been documented. In a study designed to explore that region specifically, we found plateau responses in the supra-CF region of several auditory nerve tuning curves at very high sound pressure levels (~120dB SPL). (Huang & Olson, ARO 2009, poster #623) However, a complicating issue at high sound pressure levels is the generation of subharmonics, which are likely generated in the eardrum (Dallos & Linnell 1966 JASA 40(3):561-564). Indeed, we found subharmonics in a subset of ear canal pressure we measured in gerbils, and they might have contributed to the supra-CF responses. Here we present auditory nerve tuning curves in which supra-CF neural responses were present while subharmonics were beneath the noise floor in the ear canal pressure. Thus these detections of supra-CF neural responses did not seem to suffer from subharmonic "contamination." To probe this further, we delivered loud tones and compared ear canal pressure and intracochlear pressure at subharmonics frequencies, and the quantitative relationship between the two reinforced that subharmonics were probably not responsible for the supra-CF neural responses we measured. It is conceivable that this subharmonic finding has at least two clinical implications. First, eardrum produced subharmonics might occur with very high power hearing aids. This could pose a problem to patients with band limited or high frequency hearing loss, since subharmonics that are within their normal-hearing frequencies could be perceived to be "louder" than the fundamental. Second, we found that the eardrum (the putative source of the subharmonics) was a reasonably effective sound radiator. Thus hearing aids that drive the eardrum directly might produce feedback

Physical Exercise Habits Correlate with Gray Matter Volume of the Hippocampus in Healthy Adult Humans

Physical activity facilitates neurogenesis of dentate cells in the rodent hippocampus, a brain region critical for memory formation and spatial representation. Recent findings in humans also suggest that aerobic exercise can lead to increased hippocampal volume and enhanced cognitive functioning in children and elderly adults. However, the association between physical activity and hippocampal volume during the period from early adulthood through middle age has not been effectively explored. Here, we correlated the number of minutes of self-reported exercise per week with gray matter volume of the hippocampus using voxel-based morphometry (VBM) in 61 healthy adults ranging from 18 to 45 years of age. After controlling for age, gender, and total brain volume, total minutes of weekly exercise correlated significantly with volume of the right hippocampus. Findings highlight the relationship between regular physical exercise and brain structure during early to middle adulthood

The Role of Forgetting in Undermining Good Intentions

Evaluating others is a fundamental feature of human social interaction–we like those who help more than those who hinder. In the present research, we examined social evaluation of those who not only intentionally performed good and bad actions but also those to whom good things have happened (the lucky) and those to whom bad things have happened (the unlucky). In Experiment 1a, subjects demonstrated a sympathetic preference for the unlucky. However, under cognitive load (Experiment 1b), no such preference was expressed. Further, in Experiments 2a and 2b, when a time delay between impression formation (learning) and evaluation (memory test) was introduced, results showed that younger (Experiment 2a) and older adults (Experiment 2b) showed a significant preference for the lucky. Together these experiments show that a consciously motivated sympathetic preference for those who are unlucky dissolves when memory is disrupted. The observed dissociation provides evidence for the presence of conscious good intentions (favoring the unlucky) and the cognitive compromising of such intentions when memory fails

Auditory Nerve Excitation via a Non-traveling Wave Mode of Basilar Membrane Motion

Basilar membrane (BM) motion and auditory nerve fiber (ANF) tuning are generally very similar, but the ANF had appeared to be unresponsive to a plateau mode of BM motion that occurs at frequencies above an ANF‘s characteristic frequency (CF). We recorded ANF responses from the gerbil, concentrating on this supra-CF region. We observed a supra-CF plateau in ANF responses at high stimulus level, indicating that the plateau mode of BM motion can be excitatory

High Frequency Plateau in Gerbil Auditory Nerve Tuning Curves

Ruggero et al. (PNAS 97(22) p.11744, 2000) compared threshold tuning curves of chinchilla basilar membrane (BM) vibrations and auditory nerve (AN) fibers. They noted that the AN tuning curves lacked the supra-CF frequency plateaus that are present in BM responses and suggested that BM vibrations do not translate into AN responses in the supra-CF frequency region. This observation is relevant to the relationship between BM motion (macromechanics) and hair cell stimulation (micromechanics). To further investigate the discrepancy, we recorded AN responses from the gerbil, concentrating on the supra-CF region of single AN fibers. We observed a supra-CF frequency plateau in AN responses at very high sound pressure levels (> 100dB SPL). This AN plateau was at least 10 to 15dB higher than what is predicted from BM plateaus. However, at high sound pressure levels, we also recorded subharmonics in the acoustic signal in the ear canal. The subharmonics were not produced by the speaker and appeared to be produced in the auditory mechanics. Dallos and Linnell (JASA 40(3) p.561, 1966) studied similar subharmonics, and concluded that they were produced in the ear drum and in the cochlea. We still need to determine whether the subharmonics are responsible for the supra-CF frequency plateaus in the AN responses or if the AN responses are due to the motion of the BM at the fundamental frequency

Children's Responses to Group-Based Inequalities: Perpetuation and Rectification

The current studies investigate whether, and under what conditions, children engage in system-perpetuating and system-attenuating behaviors when allocating resources to different social groups. In three studies, we presented young children with evidence of social group inequalities and assessed whether they chose to perpetuate or rectify these inequalities. Children (aged 3.5–11.5 years) heard about two social groups (i.e., racial or novel groups) whose members received resources unequally (two cookies versus one). Participants were then given the opportunity to distribute additional resources to new members of the same groups. In Experiment 1, when children were presented with inequalities involving groups of Blacks and Whites, older children (aged 7.5–11.5 years) rejected the status quo, providing more resources to members of groups with fewer resources (White or Black), whereas younger children (aged 3.5–7.5 years) perpetuated the status quo. In Experiments 2 and 3, the inequalities involved Asians and Whites and novel groups. Children of all ages perpetuated inequality, with rectification strategies applied only by older children and only when Black targets were involved in the inequality. Equal sharing occasionally occurred in older children but was never a common response. These findings provide evidence that system-perpetuating tendencies may be predominant in children and suggest that socialization may be necessary to counter them.Psycholog

Judgements of the Lucky Across Development and Culture

For millennia human beings have believed that it is morally wrong to judge others by the fortuitous or unfortunate events that befall them or by the actions of another person. Rather, an individual’s own intended, deliberate actions should be the basis of his/her evaluation, reward and punishment. In a series of studies we investigate whether such rules guide the judgments of children. The first three studies demonstrate that children view lucky others as more likely than unlucky others to perform intentional good actions. Children similarly assess the siblings of lucky others as more likely to perform intentional good actions than the siblings of unlucky others. The next three studies demonstrate that children as young as 3 years believe that lucky people are nicer than unlucky people. The final two studies find that Japanese children also demonstrate a robust preference for the lucky and their associates. These findings are discussed in relation to Lerner’s just world theory and Piaget’s immanent justice research and in relation to the development of intergroup attitudes.Psycholog

Proving Our Maternal and Scholarly Worth: A Collaborative Autoethnographic Textual and Visual Storying of MotherScholar Identity Work during the COVID-19 Pandemic

Pivoting to remote work as female academics and to schooling our children from home as mothers in March 2020 marked a dramatic shift in how we enact our MotherScholar identities. This collaborative autoethnographic study employs a modification of interactive interviewing and photovoice to produce verbal and visual text of COVID-19 MotherScholar identity work for analysis. Thematic analysis results in themes of maternal interruptions, professional interruptions, maternal recognition, and professional recognition. Of note, our MotherScholar interactivity functioned as identity work as we sought and granted legitimacy to one another’s’ COVID-19 MotherScholar identities. Of particular concern to us is how institutions of higher education are (dis)enabling socially supportive MotherScholar interactivity during COVID-19 conditions that persist at the time of this writing and how they intend to address social support needs sustainably into the future