DOI: 10.5061/dryad.9ghx3ffpv
title: Data from: cultural attraction in pottery practice: group-specific shape transformations by potters from three communities

description: Pottery is a quintessential indicator of human cultural dynamics. Cultural
 alignment of behavioral repertoires and artifacts has been considered to
 rest upon two distinct dynamics: selective transmission of information and
 culture-specific biased transformation. In a cross-cultural field
 experiment, we tested whether community-specific morphological features of
 ceramic vessels would arise when the same unfamiliar shapes were
 reproduced by professional potters from three different communities who
 threw vessels using wheels. We analyzed the details of the underlying
 morphogenesis development of vessels in wheel throwing. When expert
 potters from three different communities of practice were instructed to
 faithfully reproduce common unfamiliar model shapes that were not parts of
 the daily repertoires, the morphometric variation in the final shape was
 not random; rather, different potters produced vessels with more
 morphometric variation among than within communities, indicating the
 presence of community-specific deviations of morphological features of
 vessels. Furthermore, this was found both in the final shape and in the
 underlying process of morphogenesis; there was more variation in the
 morphogenetic path among than within communities. These results suggest
 that the morphological features of ceramic vessels produced by potters
 reliably and nonrandomly diverge among different communities.
description: 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.
description: # Data from: cultural attraction in pottery practice: group-specific shape
 transformations by potters from three communities --- Experimental data
 used in "Cultural attraction in pottery practice: group-specific
 shape transformations by potters from three communities".
 Methodological Information: see the manuscript methods section or the
 methods section of the Dryad dataset (DOI:10.5061/dryad.9ghx3ffpv) for
 details. Briefly, the dataset contains the two-dimensional outlines of the
 clay form as a function of time extracted from the video recordings of a
 cross-cultural experiment with 21 potters from three different cultural
 backgrounds (French and two Indian communities--Prajapati and Multani
 Kumhar). ## Description of the Data and file structure ## Summary Metrics
 * File count: 1 * Total file size: 713 MB * File formats: .mat ## Table of
 Contents * Pottery_Morphogenesis_Data.mat ## Setup * Unpacking
 instructions: n/a * Recommended software/tools: Matlab version 2023b. ---
 ## File/Folder Details ## Details for: Pottery\_Morphogenesis\_Data.mat *
 Description: Data of the two-dimensional outlines of the clay form as a
 function of time extracted from the video recordings of a cross-cultural
 experiment with 21 potters from 3 different cultural backgrounds (French
 and two Indian communities--Prajapati and Multani Kumhar) replicating 5
 specimens of 4 model vessel types (cylinder, bowl, sphere, and vase) with
 2 different quantities of clay (0.75 kg and 2.25 kg). * Format(s): .mat *
 Size(s): 713 MB * The table array "Pottery_Data" stores the
 following variables for each trial: * Potter: Potter ID and community
 (e.g., 'French9', 'Prajapati6'). * Type: The name of
 the model vessel type replicated and mass of clay used (e.g.,
 'Cylinder0.75', 'Vase2.25'). * Trial: Trial number
 (1-5). * Outline: Cell arrays that store multiple outlines (first column:
 the onset of the forming phase (t0), last column: the end of the forming
 phase) from each trial. Each cell contains 2D outline data extracted from
 video images of the clay body profile following each fashioning gesture. *
 Time: Cell arrays that store time stamps corresponding to multiple
 outlines stored in the column "Outline" (first column: the onset
 of the forming phase (t0), last column: the end of the forming phase) from
 each trial.