Preliminary Results of Psychology Experiment Research Proposal

PRELIMINARY RESULTS For Group Research proposal ( Genevieve )
Previous studies support the efficiency of the proposed statistical
method to measure perception of body sizes allocated to different
categories.
Using a Linear regression analysis, we will plot the mean size
judgment given to each of the seven body categories, on linear
axes. The Alexi Et al., 2018 study data showed that mean body size
judgments increase monotonically, and almost linearly with
physical body size (R2 = 0.99 for linear fit). This suggests that the
size categories were perceived as equidistant. We expect our
estimated slope to approximate that found by Cornelissen and
colleagues (Cornelissen, et. al., 2016) which was (0.72)..
Following the conventions of Cicchini, et al. 2012
we will define a regression index as the difference from unit slope,
an index ranging from zero to 1 (where 1 = total regression to the
mean).

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Body category 1 2 3 4 5 6 7
Mean standard Deviation 0.3 0.3 0.3 0.3 0.3 0.3 0.3
0.5
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7.5
1
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0.3 0.3 0.3 0.3 0.3 0.3 0.3
Chart Title
Body category Mean standard Deviation
“ Average performance in the bodyline task. (A) Mean size judgments given to each of the
seven categories of body, which varied from very thin to very overweight. Error bars
represent ± 1 s.e.m. The solid line represents the best fitting linear regression (slope 0.68, R2
= 0.99). The dotted line represents linear use of the bodyline, without scaling. (B) Average
precision thresholds, given by standard deviation of bodyline judgements, as a function of
body category. Bars show 95% confidence intervals, almost all of which span the mean,
suggesting that precision (D) Magnitude of serial dependence as a function of precision
thresholds. There is a strong and significant correlation, with higher thresholds leading to
greater dependency, as predicted by the Kalman filter model. The top right data point in (D)
is not an outlier but nevertheless we re-ran the analysis without this individual. The
correlation remained highly significant: r(102) = 0.56, p < 0.0001.”