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The current study evaluated sex differences in (1) self-perceptions of everyday and academic spatial ability, and(2) metacognitive monitoring accuracy for measures of spatial visualization and spatial orientation.

Acrossmultiple spatial measures, female students displayed lower confidence in their item-level monitoring and globalassessments of performance than did male students, even when no actual differences in spatial performanceoccurred. Women were also less confident in their self-assessments of their visual-spatial ability for scientificdomains than were men. However, the absolute and relative accuracy of CJs did not differ as a function of sexsuggesting that women can monitor their spatial performance as well as men.

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Thus, any gender differences in confidence couldarise from (somewhat) accurate monitoring of performance or from gender biases in makingconfidence judgments. Thus, if gender differences occur in confidence, will they remain whengender differences in performance is statistically controlled?

Thus,whether gender differences will occur in confidence for this task remains an open question. Asimportant, we also investigated whether gender differences occur in confidence when taskperformance (i.e., estimation precision) is controlled. This analysis is critical because whengender differences occur in performance and in confidence, then the former differences inperformance could (appropriately) be producing the gender differences in confidence.

To date, few investigations are available about gender differences in trial-by-trial confidencejudgments for math tasks, and that evidence is mixed.

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As with other metacognitive judgments (e.g.,judgments of learning), confidence judgments are not based on direct access to how preciselynumbers are represented in memory. Rather, theories of metacognition distinguish between twotypes of information that can be used as a basis for judgments (e.g., Koriat 1997; Koriat andAckerman 2010; Koriat and Levy-Sadot 1999). Theory-based judgments are informed bypeople’s naive beliefs about learning or their perceptions about their own abilities. In contrast,experience-based judgments are informed by on-line monitoring during task performance. In thenumber-line estimation task, both of these factors could influence confidence judgments aboutestimation performance.

Second, given that gender differencesdo occur in number-line estimation performance, any gender differences in confidence couldarise because people’s confidence tracks their performance.

Given such gender differences in number-line estimation performance, will gender differencesalso occur in confidence? Answering this question is important for a couple reasons. First, ifgirls/women are less confident in their estimation performance (as compared to boys/men),differences in confidence could partly be contributing to the differences in performance (for anexample in the context of the mental rotation task, see Estes and Felker 2012).

To foreshadow, such gender differences in number-line estimation performance also occurred in the present research, which motivated our focuson confidence.

Consistent with the above rationale, gender differences have been observed in number-lineestimation performance across development and for various numerical scales, with mediumeffect sizes on average (Bull et al. 2013; Gunderson et al. 2012; Hutchinson et al. 2019;LeFevre et al. 2010; Reinert et al. 2017; Thompson and Opfer 2008).

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Thus, to motivate our interest in confidence, we begin by first considering why (and whether)gender differences occur in number-line estimation performance.

To the extent that space and number are intertwined in the number-line estimation task – the focaltask in our analyses – one might anticipate gender differences due to the inherent spatial character-istics of the task.

The present research evaluates the extent to which gender differences arise in confidence onnumber-line estimation, a task which taps the fundamental ability to estimate numerical magnitude(and is predictive of future math achievement; e.g., Bailey et al. 2014; Booth and Siegler 2006, 2008;Fazio et al. 2014; Fuchs et al. 2010; Geary 2011; Schneider et al. 2018; Siegler 2016; Siegler et al.2011, 2012; Siegler and Thompson 2014; Tosto et al. 2018).

Does a gender gap occur in which girls are less confident than boys when they are engaged inmath tasks such as number-line estimation?

Boys/men were more precise (g = .52) andmore confident (g = .30) in their estimates than were girls/women. Linear mixed modelanalyses of the trial-level data revealed that girls’/women’s estimates had about 31%more error than did boys’/men’s estimates, and even when controlling for precision, girls/women were about 7% less confident in their estimates than were boys/men.

Prior research has found gender differences in spatial tasks in which men perform better,and are more confident, than women. Do gender differences also occur in people’sconfidence as they perform number-line estimation, a common spatial-numeric taskpredictive of math achievement?

This Mini-Review presents considerable evidence in sup-port of the thesis that females and males see the world dif-ferently and that this reflects corresponding sexdifferences in the human visual system

In short, sex differ-ences in the human visual system, although controversial,are undeniable. Additional investigation of sex differencesin the human visual system would contribute to analready considerable amount of evidence in support of sexdifferences in the nervous system generally and stronglycounter the traditional assumption in many fields of neu-roscience research that sex differences are negligible ornonexistent (Cahill, 2006; Cahill and Aswad, 2015).

Although some of these tasks (e.g., mental rotation) aresometimes associated with visual processing in the dorsalstream (Podzebenko et al., 2002), it is possible that sexdifferences observed in various measures of visuospatialability reflect differences in cognition rather than invision, which again highlights the requirement for addi-tional studies of sex differences in human perception andcognition in general.

engage human visual and cognitive systems (including thedorsal visual stream), with fairly disparate tasks showingvarying degrees of sex differences in performance (Millerand Halpern, 2014).

Over the past several decades, many studies have reportedsex differences in visuospatial ability, in particular, superi-or performance in males ( Maccoby and Jacklin, 1974;Linn and Petersen, 1985; Voyer et al., 1995). Unfortu-nately, visuospatial performance has been measured byextremely diverse stimuli and tasks that differentially

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In anexhaustive review of experiments on sex differences inlaterality, Hiscock et al. (1995) concluded that most if notall findings of vision-related sex differences in lateralitywere genuine.

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In short, although sex differencesin color vision may be related to both retinal and corticalfactors, additional studies are required to validate and elu-cidate such differences.

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Although this finding has also been observed inother mammals (Seymoure and Juraska, 1997), some havespeculated that sex differences in visual acuity in humansare related to the roles that men and women played inearly human hunter–gatherer societies, in which malesmay have been required to be able to identify prey orthreats at greater distances (Silverman and Eals, 1992;Sanders et al., 2007; Stancey and Turner, 2010; Abramovet al., 2012a).

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Theseauthors speculated that this sex difference reflects differ-ences in visual pattern analysis mode in which femalesemphasize use of low spatial frequencies that carryinformation about overall object form, whereas malesuse a more “segregative” mode that emphasizes individ-ual objects and fine detail inherent in high spatial fre-quency visual input.

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This section summa-rizes sex differences observed in standard psychophysicalstudies of visual perception and also presents related find-ings from neurophysiological and neuroimaging studies.

additional sex differences in visual perception and itsbasis in the human visual system and in the visual cortexin particular.

In short, sex differences in both bodysize and brain size predict sex differences in visual percep-tion. This Mini-Review summarizes and discusses many

In contrast to reproductive capacity, sex differencesin human brain function are largely a matter of degree.This Mini-Review of sex differences in the human visualsystem presents a large body of evidence indicating thatsex differences in visual perception and its neural basis arereal and lends support to the folk belief that males andfemales really do see the world differently, even if only toa degree.

This Mini-Review summarizes a wide range of sex differ-ences in the human visual system, with a primary focuson sex differences in visual perception and its neuralbasis. We highlight sex differences in both basic andhigh-level visual processing, with evidence from behavior-al, neurophysiological, and neuroimaging studies. Weargue that sex differences in human visual processing, nomatter how small or subtle, support the view that femalesand males truly see the world differently.

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We found that, for about a third of these tests, females performed significantly worse thanmales. In no paradigm did females outperform males.

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It is unclear why our results differ from previous studies, but it is possible that the small methodologicaldifferences we describe may have a large effect, and further studies should explore these effects in more detail.

Our results stand in contrast to many previous studies of sex differences in visual perception.

It is important to emphasize that visual tasks also rely on non-visual processes. It is therefore possible thatsome of the differences we report may be non-visual in nature.

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Our results are in line with studies demonstrating no correlations between similar paradigms in visual per-ception 22,39,53–55 .

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Using fifteen differentvisual tasks and more than 870 participants, we found that males significantly outperformed females in simple RT,visual acuity, visual backward masking, motion direction detection, biological motion, and the Ponzo illusion. Wedid not find significant sex differences for contrast detection threshold, visual search, orientation discrimination,the Simon effect, and four of five visual illusions.

Figure 5.

Table 3.

For Sample C (Table 1), we found a significant sex difference for the Ponzo illusion with amedium effect size (Table 3, Fig. 5; t(170) = −3.15, p = 0.002, d = 0.24). Females were 3.5% more susceptible tothe illusion than males (−11.8 vs −8.3%).

Results from three tests differed between males and females, i.e. RT, biological motion (inverted condition at800 ms) and motion direction. In all cases, males performed better than females (Fig. 4).

Using the 25 elements grating, females needed an SOA of 47.78 ms to reach the criterion level of 75%correct answers, whereas males needed an SOA of 39.9 ms (t(624) = 2.09, p = 0.03, d = 0.17) to reach the criterionlevel (see Table 2). When using the 5 elements grating, both males and females showed longer SOAs than with the25 elements grating; females again needed longer SOA than males (113.1 vs. 99.93 ms, respectively; t(624) = 2.57,p = 0.01, d = 0.20).

Females (22.66) as compared to males (21.19) did not differ in their vernier duration(t(624) = 1.21, p = 0.22; Table 2).

Males had a higher visual acuity compared to females (1.61 vs 1.46; t(623) = −4.37, p < 0.001).The effect size was medium (d = 0.35).

In detail, we found significant differences in Sample A, with 626 participants, on visual acuity and visual back-ward masking with both masks, but not for the unmasked vernier (see Fig. 3 and Table 2).

Out of the 10 perceptual tests (3 tests for 626 participants and 7 additional tests for 200participants), males performed significantly better than females in 5 tests: visual acuity, visual backward maskingwith 25 and 5 gratings, RT, biological motion, and motion direction.

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It is then possible that cyclingestrogen and progesterone or their interaction enhance PC-processing in women.

In addition to estrogen, progesterone is implicated in visualprocessing

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However, if some of our female subjects areindeed heterozygous carriers for red-green deficiency, evidenceindicates that the advantage in red-green contrast sensitivitymight belong to men due to deficient red-green discriminationfound in heterozygous carriers [24-26].

A review byParlee [33] highlighted evidence for cyclical effects on visualprocessing, and a later review [34] of this research suggests thereis an increased cortical capacity for visual information processingin women during peak estradiol levels of the menstrual cycle.

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While neither stimulus isabsolutely processed by one parallel pathway or the other, it isreasonable to assume that PC processes underlie sensitivity tothe small, red-green target. Likewise, processing for the large,drifting stimulus is certainly biased toward the MC pathways.

Men had lower contrast thresholdsthan women to the large, achromatic, drifting stimulus, but thedifference was not statistically significant for this target.

In this experiment, we found that women were moresensitive than men to the contrast changes in the small, red-green, stationary stimulus, which is more likely to be processedstrongly by the PC pathway.

Figure 2

There was no main effect of gender (F = 0.50,p = 0.48), but there was a significant interaction of gender andstimulus type on reaction times (F = 4.13, p = 0.04). Unlike theresults for contrast thresholds, there was no gender difference inreaction times for either the MC or PC-biased stimulus.

Both men andwomen had significantly lower mean reaction times for the MC-biased stimulus than for the PC-biased stimulus (F = 93.0, p <0.001).

The main effect of genderwas not significant (F = 2.43, p = 0.12), but there was a significantinteraction of gender and stimulus type (PC-biased vs. MC-biased) on contrast thresholds (F = 4.80, p = 0.03). As shown inFigure 1, women were more sensitive than men to the PC-biasedstimulus (t = 1.94, p = 0.05), but men and women were equallysensitive to the MC-biased stimulus (t = -1.22, p = 0.23).

As shown in Table 1, contrast thresholds for the MC-biased stimulus were significantly lower than for the PC-biasedstimulus (F = 246, p < 0.001).

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Theresults of these studies suggest that men may rely more on MCprocessing, while women may rely more on PC processing.

Although previous studies of gender effects on visualprocessing are heterogeneous, as a group they suggest thepossibility of sexual dimorphism in parallel visual processing[5].

Neurons in the MC pathwayare more sensitive to object location, movement, low spatialfrequency and global analysis of visual scenes. Neurons in the PCpathway are thought to be more involved with object and patternrecognition as well as color (in particular, red-green) opponency[3,4].

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The results of this experiment add to the body of evidence that women may relymore on parvocellular visual processes than men.

We present a limited review of the literature on gender differences in visualprocessing. We then add evidence to that body of literature, reporting the resultsof an examination of gender differences in response to stimulus conditions favoringmagnocellular (MC) and parvocellualr (PC) processing.

Governor Ronald Reagan, who was coincidentally present on the capitol lawn when the protesters arrived, later commented that he saw "no reason why on the street today a citizen should be carrying loaded weapons" and that guns were a "ridiculous way to solve problems that have to be solved among people of good will." In a later press conference, Reagan added that the Mulford Act "would work no hardship on the honest citizen."

Perhaps the most immediate benefit of capturing content outsideour heads is that we escape what I call the “reactivity loop”—thehamster wheel of urgency, outrage, and sensationalism thatcharacterizes so much of the Internet. The moment you firstencounter an idea is the worst time to decide what it means. Youneed to set it aside and gain some objectivity.

When you use up too much energy taking notes, you havelittle left over for the subsequent steps that add far more value:making connections, imagining possibilities, formulating theories,and creating new ideas of your own

The proposition that any of this book’s content or its contributors are racist, because they might make people feel uncomfortable, is an increasingly popular strategy employed to silence expert views on politicised ideological grounds.

Published criticisms of this excellent book bear the hallmarks of a style of racism that is extraordinarily difficult to counter, because so few people have the intellectual training to understand the difference between evidence-based accounts of Indigenous Australia and popular mythologies that misrepresent the facts. These criticisms are entirely unreasonable.

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It is surprising that similar studies in vision research are few and often under-powered 16–19 (with the notableexception of the well-established male preponderance of red-green color blindness 20,21 or sex differences in eyemovements 22 ).

Taken together, these studies revealmixed and complex effects of sex on visual perception. Moreover, it is clear that a comprehensive study on sexdifferences is missing from the literature.

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We report the results of fifteenperceptual measures (such as visual acuity, visual backward masking, contrast detection threshold ormotion detection) for a cohort of over 800 participants. On six of the fifteen tests, males significantlyoutperformed females. On no test did females significantly outperform males. Given this heterogeneityof the sex effects, it is unlikely that the sex differences are due to any single mechanism.

Further, we argue that theloss of function in insula/temporal areas may be directly related totool-use deficits seen in conceptual apraxia.

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fMRI showed that primary activations for identifying incorrect tooluse were found at temporal cortex and insula, while activationsfor correct tool use were seen along the canonical parietofrontaltool use network. Source localization analysis of EEG waveformsprovided additional information about the temporal evolution ofthese activations; insula, temporal cortex, and cuneus were exclu-sively active to incorrect tool use 0–200 ms following image onset,while occipitotemporal areas were exclusively active to correct tooluse 300–400 ms after image onset.

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If the tool–object relationship is determined to be contextuallyappropriate, no (tool-use specific) error signal arises from insula/superior temporal cortex. In this case, the parietofrontal networkwould then derive the adequate (task relevant) sensorimotor repre-sentation and motor plan for that tool–action goal pair. Alternatively,if the tool–object relationship is determined to be contextuallyinappropriate, perhaps the insula/superior temporal areas serve togenerate an error signal allowing for appropriate perception of tooluse error.

tool–object interactions.

Although currently speculative, our temporal and spatial resultsallow us to suggest that insula and superior/middle temporal cortexmay serve as a “gatekeeper,” evaluating the contextual correctness of

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Precuneus

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This relates to thecurrent study in superior temporal/insula activations seen in thejudgment of too use in an incorrect context, and further supportshigh-level visual functions in superior temporal areas cortex.

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Unlike the findings of correct over incorrect context, incorrectover correct contextual tool use activated novel areas that lie ventralto the parietofrontal regions, as well as on the mesial brain sur-face, particularly the insula, superior and middle temporal cortex,posterior cingulate, and cuneus/precuneus.

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Event-related fMRI analysis showed distinct activationsin bilateral insula, superior temporal cortex, anterior cingulate, andposterior cingulate for tool use in incorrect contexts (Figure 3).Bilateral activations for tool use in correct contexts tool use wereseen in posterior temporal areas and occipital cortex extendingalong the temporal–parietal–occipital junction, superior parietalcortex, premotor areas, lateral prefrontal areas, and anterior cin-gulate (Figure 3). EEG results largely confirm the fMRI data, whilefurther elaborating the temporal activation features. With analysisof EEG data focused on time bins identified through our previouswork (Mizelle and Wheaton, 2010b), we observed early activations(e.g., during the first 200 ms following image onset) exclusively forincorrect over correct tool use in temporal cortex, insula, cuneus, andposterior cingulate (Figure 5). Later time windows (300–400 ms)showed occipital and temporal activity (Figure 5) for identifica-tion of correct over incorrect tool use exclusively.

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A briefdeflection was seen following onset of the cue, and large, sustaineddeflections were present following onset of the image. As comparedto tool-only images, these responses were larger for correct andincorrect tool use at temporal and parietal areas. Waveforms for cor-rect and incorrect tool use diverged at two times following onset ofthe image (0–200 and 300–400 ms following image onset; Figure 4).This was most noticeable at bilateral temporal and parietal regions,where activation for incorrect use was greater immediately fol-lowing image onset (0–200 ms) and later at occipital, parietal, andtemporal regions (300–400 ms), where activation was greater forcorrect over incorrect tool use.

However, at 300–400 msafter image presentation (Figure 5; Table 5), activation differencesexclusive for identifying correct over incorrect tool use were seen atoccipitotemporal areas and cuneus.

From 100–200 ms post image presentation (Figure 5; Table 4),these activation differences shifted posteriorly to cuneus, lingualgyrus, insula, superior temporal cortex, and were still exclusive toincorrect over correct tool use.

When thesewaveforms were subjected to analysis (Figure 5; Table 3), sLO-RETA showed early activation differences (0–100 ms post imagepresentation) exclusively for identifying incorrect over correct tooluse predominantly at insula, superior temporal cortex, and anteriorand posterior cingulate.

For both [cor-rect > tool] and [incorrect > tool] comparisons, primary acti-vations were generally seen at premotor areas, inferior frontalgyrus, SPL, IPL, posterior temporal cortex, middle and inferioroccipital gyri, cuneus, lingual gyrus, insula, fusiform gyrus, andcingulate gyrus.

This analysisshowed that bilateral premotor and parieto-occipital areas wereactive in comprehension of correct tool use (Figure 3; Table1), while bilateral regions along the insula, superior tempo-ral cortex, mesial prefrontal cortex, and posterior cingulatewere active in comprehension of incorrect contextual tool use(Figure 3; Table 2).

Overall subjects were 95% accurate in their assessment of correctversus incorrect contextual tool–object interaction.

In other words, subjects were notmore or less accurate for either image category.

A role is suggested for theventral stream in providing semantic/contextual information toparietofrontal areas prior to interaction with a tool or object (Creemand Proffitt, 2001b; Valyear and Culham, 2010). In our previouswork, a distinct temporal–insula–precuneus–cingulate network wasengaged in differentiating matching from mismatching tool–objectpairings (Mizelle and Wheaton, 2010b).

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Others using ERPanalyses have identified the N400 effect in response to identi-fication of anomalous tool use (Sitnikova et al., 2003, 2008).Similarly, this response has been seen in extracting movement-related semantic information, such as identifying the incorrectconclusion of an action sequence (Reid and Striano, 2008) andin determining uncooperative hand–hand interactions (Shibataet al., 2009).

Others have evaluated the understanding of toolsimilarity based on action relatedness (comparing tools used inthe same way) or functional relatedness (comparing tools usedin the same context; Canessa et al., 2008), and highlighted theimportance of retrosplenial and inferotemporal cortex in under-standing functional properties of tools.

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We identified distinct regional and temporalactivations for identifying incorrect versus correct tool use. The posterior cingulate, insula, andsuperior temporal gyrus preferentially differentiated incorrect tool–object usage, while occipital,parietal, and frontal areas were active in identifying correct tool use. Source localized EEGanalysis confirmed the fMRI data and showed phases of activation, where incorrect tool-useactivation (0–200 ms) preceded occipitotemporal activation for correct tool use (300–400 ms).

In the currentwork, we used event-related electroencephalography (EEG) and functional magnetic resonanceimaging (fMRI) to determine neural correlates for differentiating contextually correct and incorrecttool use.

I think it may have been the British Library interview in which Wengrow says something like, you know, no one ever challenges a new conservative book and says, so and so has just offered a neoliberal perspective on X. But when an anarchist says something, people are sure to spend most of their time remarking on his politics. I think it's relevant that G&W call out Pinker's cherry-picking of Ötzi the ice man. They counter this with the Romito 2 specimen, but they insist that it is no more conclusive than Ötzi. So how does a challenging new interpretation gain ground in the face of an entrenched dominant narrative?

The last element in his file system was an index, from which hewould refer to one or two notes that would serve as a kind of entrypoint into a line of thought or topic.

A spike in fears about new immigrants and newly emancipated black people reproducing at higher rates than the white population also prompted more opposition to legal abortion.

Incubate Our Ideas Over Time

Your mind is for having ideas, not holding them.—David Allen, author of Getting Things Done

If you're in software development, start your zettelkasten by documenting the step-by-step instructions to fresh install your development environment. Windows Utilities, Dev Tools, IDE, all those config options not already in your dotfiles, etc...I promise it'll be useful and get you started

grayscale photograph can be converted to a dithered black-and-white image using thresholding, with the leftover amount from each pixel added to the next pixel along the Hilbert curve.

7 Notes could also focus on original thoughts, as in the Pen-sées of Blaise Pascal, the “commonplace book” of George Berkeley, or the Sudel-bücher of Georg Lichtenberg, which were devoted to original reflections ratherthan to excerpts from the writings of other authors.

An alternative kind of note-taking was encouraged in the late Middle Agesamong members of new lay spiritual movements, such as the Brethren of theCommon Life (fl. 1380s–1500s). Their rapiaria combined personal notes andspiritual reflections with readings copied from devotional texts.

Referencebooks also typically offered a larger collection of excerpts than most individualscould amass in a lifetime.

We discovered that exercise for 4th-6th postnatal weeks (juv-adol ELE), as well as a shorter exercise experience only during the 4th postnatal week (juv ELE) enable hippocampal-dependent spatial memory formation in male mice. This was not true for mice that exercised only during the 6th postnatal week (adol ELE), suggesting that the 4th postnatal week of development was particularly sensitive to the exercise experience with regard to enabling long-term memory function in a lasting manner.

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adolescent exercisers when compared to sedentary controls.

Overall, these data suggest a significant impact of ELE on enhancing hippocampal long-term potenti-ation. Although this finding is in contrast to data in adult mice demonstrating lack of enhancement in CA1-LTP after chronic voluntary wheel running9, it may implicate a specific, 1-week period of juvenile exercise that can lead to lasting changes in hippocampal CA3-CA1 circuit function and plasticity.

Therefore, synaptic plasticity was examined in the CA3-CA1 Schaffer collateral pathway of the hippocampus in sedentary and ELE mice, to test the hypothesis that ELE also leads to an enhance-ment in synaptic strength in the same region involved in enabled memory performance after juv and juv-adol ELE.

These results suggest that in both sexes, exercise taking place during a specific juvenile developmental period (P21–27) is sufficient for enhancing long-term memory for an OLM acquisition trial that is usually insufficient for long-term memory in sedentary controls, and fur-thermore, juv ELE-induced enabling of long-term memory is present at least 2 weeks after the juvenile exercise period ends.

These data suggest that performance in the OLM task can be used as a robust measure of long-term memory formation in adolescent male and female mice.

We therefore tested the following hypotheses: 1) that a learning stimulus typically insufficient for long-term memory formation in sedentary wild-type mice can become sufficient after ELE (as it does after 2–3 weeks of exercise in adulthood), and 2) the early-life timing of exercise during juvenile and/or ado-lescent periods will have a lasting impact on the duration of ELE-induced improvements in long-term memory.

We next addressed the question whether there are sex differences in daily and cumulative running distances in our three ELE groups. Juv-adol ELE male and female mice gradually increased their daily running distance over the 3-week period (Fig. 1c).

We next compared daily and cumulative running distances in 1-week runners, expecting that running distance would be significantly greater in adol ELE mice when compared to juv ELE mice (regardless of sex) given their developmental stage and body mass differences when entering running cages.

Given the developmental timing of voluntary exercise in this model, we postulated that there would be important sex-specific and running group-specific differences in weight gain and distance ran across time.

In sum, all running groups and both sexes of mice gradually and significantly increased their running distances across time. The cumulative amount of voluntary running throughout the running period was dependent on when early life exercise was initiated (in the juvenile period vs in adolescence).

These findings suggest that a longer duration of ELE expo-sure (three weeks) during juvenile/adolescence significantly reduces weight gain in male mice, whereas in female mice, presence of a stationary wheel led to greater weight gain than mice in sedentary cages without running wheel and mice that ran during adolescence.

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In this study we developed a model of voluntary physical activity during specific early life developmental periods in mice (early-life exercise, or ELE) to address the hypothesis that the timing of exercise during postnatal hippocampal maturation can lead to enduring benefits in cognitive function and synaptic plasticity.

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hysical exercise is a powerful modulator of learning and memory. Mechanisms underlying the cognitive benefits of exercise are well documented in adult rodents. Exercise studies targeting postnatal periods of hippocampal maturation (specifically targeting periods of synaptic reorganization and plasticity) are lacking. We characterize a model of early-life exercise (ELE) in male and female mice designed with the goal of identifying critical periods by which exercise may have a lasting impact on hippocampal memory and synaptic plasticity.

Our results suggest that early-life exercise, specifically during the 4th postnatal week, can enable hippocampal memory, synaptic plasticity, and alter hippocampal excitability when occurring during postnatal periods of hippocampal maturation.

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Again, support was found for the hypotheses that oxytocin creates intergroup bias because it motivates in-group favoritism. Put differently, oxytocin motivated in-group favoritism both when an intergroup compari- son was salient (experiments 1 and 2) and when such an intergroup comparison was substantially more implicit (experiments 3-5). Together, these results suggest that in-group favoritism emerges regardless of whether an explicit out-group comparison is ren- dered salient

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Results show that oxytocin creates intergroup bias because it motivates in-group favoritism and, in some cases, out-group der- ogation.

Together, these results provide additional support for the hypothesis that (/) oxytocin creates intergroup bias because (ii) oxytocin promotes in-group favoritism. There was no support for the hypothesis that (Hi) oxytocin promotes out-group derogation.

Experiment 3 thus supports the hy- pothesis that .(/) oxytocin creates intergroup bias because (ii) oxytocin promotes in-group favoritism. There was no support for the hypothesis that (Hi) oxytocin promotes out-group derogation.

Thus, there is support for the hypothesis that (/) oxytocin creates in- tergroup bias because (//) oxytocin promotes in-group favoritism. Mixed support was obtained for the hypothesis (Hi) that oxytocin promotes out-group derogation.

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In-group favoritism and out-group derogation conspire to create intergroup bias: the unfair response toward another group that devalues or disadvantages the other group and its members by valuing or privileging members of one's in-group (29). Here we predicted that (/) oxytocin creates such intergroup bias because (ii) oxytocin promotes in-group favoritism and, possibly, (///) out- group derogation.

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If in-group favoritism and out-group derogation have adaptive value and sustain in-group functioning, coordination, and co- operation, it follows that (/) throughout evolution those individ- uals who displayed in-group favoritism and out-group derogation and who detected such tendencies in others were more likely to spread than individuals lacking these capacities (5-8) and (ii) the human brain may have evolved to sustain ethnocentrism through yet-unknown neurobiological systems.

Human ethnocentrism - the tendency to view one's group as cen- trally important and superior to other groups- creates intergroup bias that fuels prejudice, xenophobia, and intergroup violence. Grounded in the idea that ethnocentrism also facilitates within- group trust cooperation, and coordination, we conjecture that eth- nocentrism may be modulated by brain oxytocin, a peptide shown to promote cooperation among in-group members.

Results show that oxytocin creates intergroup bias be- cause oxytocin motivates in-group favoritism and, to a lesser ex- tent, out-group derogation. These findings call into question the view of oxytocin as an indiscriminate "love drug" or "cuddle chem- ical" and suggest that oxytocin has a role in the emergence of in- tergroup conflict and violence.

Powerful tools can support creativity: Innovation can be facilitated by powerful tools that supply templates and support exploratory processes such as brainstorming (offering links to related concepts), state-space expl oration (trying out all permutations), idea combining (systematic pairings), rapid prototyping, and simulation modeling.

The present results ought to be considered alongside the lim-itations of this study.