Self-deception and deception of others are positively associated.

<p>Scatterplots with best-fit lines for residuals of deception (median estimate of focal individual's performance by peers – focal individual's actual performance) plotted against residuals of self-deception (self-estimate of focal individual's performance – focal individual's actual performance) based on absolute grades (red circles and red bold lines) and relative ranks (blue squares and blue dotted lines) in (a) week one and (b) week six. The residuals were obtained via a partial correlation analysis that regressed (i) self-deception against actual grade and (ii) deception against actual grade. Mean ± s.d. of absolute level of self-deception was 1.93±1.54 grades and 2.11±1.70 ranks in week one and 1.72±1.42 grades and 2.04±1.99 ranks in week six. Mean ± s.d. of absolute level of deception was 1.90±1.48 grades and 1.80±1.30 ranks in week one, and 1.27±1.03 grades and 1.86±1.59 ranks in week six.</p

Self-Deceived Individuals Are Better at Deceiving Others

<div><p>Self-deception is widespread in humans even though it can lead to disastrous consequences such as airplane crashes and financial meltdowns. Why is this potentially harmful trait so common? A controversial theory proposes that self-deception evolved to facilitate the deception of others. We test this hypothesis in the real world and find support for it: Overconfident individuals are overrated by observers and underconfident individuals are judged by observers to be worse than they actually are. Our findings suggest that people may not always reward the more accomplished individual but rather the more self-deceived. Moreover, if overconfident individuals are more likely to be risk-prone then by promoting them we may be creating institutions, including banks and armies, which are more vulnerable to risk. Our results reveal practical solutions for assessing individuals that circumvent the influence of self-deception and can be implemented in a range of organizations including educational institutions.</p></div

Summary of demographic variables of study participants.

<p>*Participants' parent's professions were assigned to categories specified by the Office of National Statistics (ONS). Occupational data from the ONS were used as a reference and the gender-specific median annual full-time London earnings of the relevant category were assigned to each parent. The earnings of both parents were added together to obtain the family income. For the partial correlation analyses, the Hollingshead four factor index <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104562#pone.0104562-Hollingshead1" target="_blank">[20]</a> was derived from individual earnings (as above) for each parent and the index for the parent with the highest earnings was used as a measure of family income. The ONS table used to calculate family income was titled: PROV - Work Region Occupation SOC10 (2) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104562#pone-0104562-t003" target="_blank">Table 3</a>.7a Annual pay - Gross 2011.</p><p>Summary of demographic variables of study participants.</p

Sample sizes and sex ratios for the twelve tutorial groups included in this study.

1<p>UCL - University College London; QMUL - Queen Mary University of London.</p>2<p>Numbers in parentheses indicate the total number of students present during the tutorial since not all students chose to participate in this study.</p><p>29 students participated from UCL^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104562#nt102" target="_blank">1</a>} and 44 students from QMUL^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0104562#nt102" target="_blank">1</a>} (total n = 73). The mean age ± s.d. of participants was 18.76±0.90 years and 85% were female.</p><p>Sample sizes and sex ratios for the twelve tutorial groups included in this study.</p

Self-deception and susceptibility to being deceived are positively associated.

<p>Scatterplots with best-fit lines for residuals of susceptibility to being deceived (median of the difference between a focal individual's estimate of peer performance and the actual performance of peers) plotted against residuals of self-deception (self-estimate of focal individual's performance – focal individual's actual performance) based on absolute grades (red circles and red bold lines) and relative ranks (blue squares and blue dotted lines) in (a) week one and (b) week six. The residuals were obtained via a partial correlation analysis that regressed (i) self-deception against actual grade and (ii) susceptibility to being deceived against actual grade.</p

Experimental stimuli for testing the role of ΔF in source segregation.

<p>Shown here are examples of (<i>a</i>) the waveform of the pulsed target signal; (<i>b</i>) the waveform of a 2-s segment of the continuous train of distractor pulses; (<i>c</i>) a waveform showing the interleaved target signal and distractor pulses; and (<i>d</i>) a spectrogram showing an interleaved target signal (2.6 kHz) and distractor pulses (1.093 kHz) separated by a ΔF of 15 semitones.</p

Phonotaxis scores as a function of frequency separation (ΔF) in a test of sound source segregation.

<p>(<i>a</i>) The absolute carrier frequencies of the distractor pulses (F) shown in relation to the magnitudes of frequency separation (in semitones) for the two target signals with carrier frequencies of 1.3 kHz (ΔF_{1.3 kHz}) and 2.6 kHz (ΔF_{2.6 kHz}). Note that for the ΔF of 3 semitones, we tested values of absolute frequency that were 3 semitones above and below each signal frequency; we designate these as ΔFs of ±3 semitones, with the positive designation corresponding to the direction of frequency change (either higher or lower) of the other distractor frequencies tested. (<i>b</i>) Mean (± SE) phonotaxis scores as a function of ΔF (n = 40). Asterisks indicate significant differences (p<0.05) in planned contrasts comparing the indicated value of ΔF to ΔF = 0. (<i>c</i>) Mean (± SE) phonotaxis scores as a function of ΔF shown separately for subjects tested with target signals having a carrier frequency of 1.3 kHz (circles and solid line; n = 20) or 2.6 kHz (squares and dashed line; n = 20). (<i>d</i>) Phonotaxis scores from (<i>c</i>) plotted as a function of the absolute carrier frequency of the distractor pulses.</p

The acoustic scene of a mixed-species breeding chorus.

<p>Spectrograms (top traces) show frequency as a function of time (amplitude shown as color intensity) and oscillograms (bottom traces) show amplitude as a function of time. In Minnesota, U.S.A., where our study was conducted, three heterospecific species that form mixed-species choruses with gray treefrogs are boreal chorus frogs, American toads, and northern leopard frogs. (<i>a</i>) The advertisement call of a male gray treefrog (<i>Hyla chrysoscelis</i>) (see text for description). (<i>b</i>) American toads (<i>Bufo americanus</i>) produce a long (≈5–50 s), trilled call (≈35–45 pulses s⁻¹) with a single spectral component (≈1.7–2.0 kHz) that falls between the two spectral components of the gray treefrog call <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021191#pone.0021191-Howard1" target="_blank">[53]</a>; a 2-s segment of a longer call is shown here. (<i>c</i>) Boreal chorus frogs (<i>Pseudacris maculata</i>) produce a pulsed advertisement call of approximately 750–950 ms in duration (≈13–18 pulses s⁻¹) and with a bimodal frequency spectrum having peaks at about 1.9 kHz (−8 to −22 dB) and 3.8 kHz (0 dB) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021191#pone.0021191-Bee8" target="_blank">[54]</a>. (<i>d</i>) Northern leopard frogs (<i>Rana pipiens</i>) also produce a relatively long (≈2–5 s), trilled call (termed a “snore”) that is fairly broadband (≈0.5–2.0 kHz), with dominant frequencies ranging from about 0.9 to 1.5 kHz <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021191#pone.0021191-Larson1" target="_blank">[55]</a>. (<i>e</i>) A mixed-species chorus in Minnesota comprising calls by all four species depicted in (<i>a</i>–<i>d</i>). All recordings were made with Sennheiser microphones (ME66 or ME67) and a Marantz PMD670 recorder. Spectrograms were generated using an FFT window size of 1024 points with Blackman-Harris windows.</p

Results from no-choice tests of audibility.

<p>Depicted are the proportions of subjects that responded to unimodal calls presented at 67 dB SPL with carrier frequencies as indicated along the x-axis. Insets depict the power spectra of three selected stimuli showing relative amplitude (from 0 dB to −36 dB in 6-dB steps; y axis) as a function of frequency (from 0 to 4 kHz, 0.5-kHz steps; x-axis). The sample size for each bar was n = 12 for all stimuli except that at 4.0 kHz, for which the sample size was n = 11. Asterisks indicate significant differences (p<0.05) in one-tailed binomial tests of the hypothesis that the represented proportion exceeded the expected null proportion of  = 0.2 (dashed line).</p

Results of two-choice discrimination tests for pulse rate selectivity.

<p>Females were given a choice between two alternating stimuli that differed in pulse rate (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021191#s4" target="_blank">Materials and Methods</a>). Results are shown for tests in which both alternatives had carrier frequencies of (<i>a</i>) 1.3 kHz (−9 dB) and 2.6 kHz (0 dB), (<i>b</i>) 1.3 kHz, or (<i>c</i>) 2.6 kHz. Each line connects two points that show the proportions of females (n = 12 per test) choosing the alternative with a conspecific pulse rate (45.5 pulses s⁻¹) and a call with either a slower (23 pulses s⁻¹; solid line) or faster (91 pulses s⁻¹; dashed line) pulse rate. Insets depict the power spectrum (based on the 45.5 pulses s⁻¹ call) for the alternatives in each corresponding two-choice test showing relative amplitude (from 0 dB to −36 dB in 6-dB steps; y-axis) as a function of frequency (from 0 to 4 kHz, 0.5-kHz steps; x-axis). In all tests, females chose the alternative with a conspecific pulse rate significantly more often than expected by chance (two-tailed binomial ps<0.05). These results confirmed that females were selective for conspecific pulse rates with unimodal calls having carrier frequencies of either 1.3 kHz or 2.6 kHz.</p