Data from: cultural attraction in pottery practice: group-specific shape transformations by potters from three communities

Potters from three communities were instructed to faithfully reproduce four different model shapes with the thinnest walls possible using two different quantities of clay (0.75 kg or 2.25 kg), giving a total of eight experimental conditions. The four shapes (referred to as Cylinder, Bowl, Sphere, and Vase, respectively) were presented as pictures without providing any indication of the absolute dimensions to be produced. The four shapes were not part of any of the potters’ daily repertoire. Potters produced five specimens for each of the eight vessel types. The experimental sessions were video-recorded under standardized conditions using a Panasonic NV-GS320 camcorder. The camera was fixed on a tripod with lens orientation centered on the vertical rotation axis of the wheel. The camera was positioned at a height of 30 cm above the level of the wheel at a horizontal distance of 4-6 m. The lower edge of the video scene was aligned with the center of the wheel. The zoom was adapted to fully cover a 36-cm high by 42-cm wide calibration object (inverted T-shape) placed on the wheel at the start of each recording. For each trial, the images of the clay body profile after each fashioning gesture were extracted from the video frames (image resolution: 720 x 576 pixels; video sampling frequency: 25 fps). The first image captured the profile immediately following the (centering and opening) pre-forming phase and the last image captured the final profile; the intervening images captured the intermediate profiles during form development. This succession of profiles captured the vessel’s morphogenesis. The overall duration of the forming process was also analyzed. From the images, we extracted the 2D coordinates of the right half of the cross-sectional profiles by tracing them out on a Cintiq 21UX Wacom (Kazo, Japan) tablet with an integrated screen. The profile coordinates were converted from pixels to centimeters using a calibration factor obtained from the digitized dimensions of the calibration object. The profiles were re-sampled to generate an equal number of points at regular height intervals along the vertical (Y) axis and the resulting coordinates were smoothed with a low-pass filter. Because wheel-thrown vessels are typically axisymmetric, profiles were subsequently converted to full pot outlines by multiplying the horizontal (X) coordinates by -1 to create the corresponding left edge. Of the total 840 vessels thrown (twenty-one potters, each throwing five specimens of eight different vessel types), 12 vessels were not included due to problems with the video recording.