Table 1.
Experimental details on the blind test artefacts (tool use, prehensile mode, blank, cleaning protocol).
Fig 1.
Macroscopically visible residues before washing (from left to right): BT9 (wood scraping), BT17 (bone grooving), BT23 (antler scraping).
Fig 2.
comparison of residue appearance under V16 Zeiss zoom microscope with magnifications up to 180x (a & c) and reflected light metallurgical microscope (Zeiss AxioImager) with magnifications up to 500x: b &d) images from the same residues.
a & b) wood from retouching; c & d) antler from retouching (a: 160x; b, c, d: 100x).
Table 2.
Interpretations of Analyst 1 and 2 based on in situ analysis of residues, directly on the stone artefacts (BT: blind test; CL: confidence level—on scale from 0 = uncertain to 4 = certain).
Scores: 0 (wrong), 0,5 (partially correct), 1 (correct).
Table 3.
Interpretations of Analyst 1 and 2 based on an analysis of extracted residues under transmitted light.
Staining was applied when considered relevant by the analyst (BT: blind test; CL: confidence level—on scale from 0 = uncertain to 4 = certain). Scores: 0 (wrong), 0,5 (partially correct), 1 (correct).
Table 4.
Interpretations of Analyst 3 based on a broad screening of the blind test artefacts.
Scores: 0 (wrong), 0,5 (partially correct), 1 (correct).
Table 5.
Summary of results based on in situ observation (up to 180x) for the distinction between used and unused pieces; per category of artefacts (percentages are calculated based on identified pieces).
Table 6.
Summary of results based on transmitted-light observations for the distinction between used and unused artefacts; per category of artefacts.
Fig 3.
Residues identified on BT6 (unused) as described during blind test.
a) White use-residue with evident directionality (indicated by arrow) along Edge A of the ventral surface; b) high magnification image of white, amorphous residue on tool edge; c) possible fatty deposits (beneath scale bar); d) collagen residue stained with Orange G, as viewed under transmitted light.
Fig 4.
Residues identified on BT16 (unused) as described during blind test.
a-b) White use-residue with evident directionality (diagonal from edge); c) unidentified residue film; d) collagen residues stained with Orange G, transmitted light.
Fig 5.
Re-evaluation of residues identified on BT16 (unused).
a) Wood from retouching stained with orange G, after washing out not correctly (400x); b) Wood from retouching, after washing out correctly (400x); c) Wood partly stained with Orange G due to not washing out correctly the stain (200x).
Fig 6.
Assumed use-residues identified on BT8 (unused) as described during blind test.
a) Blood residue on the distal retouched end of the flake; b) fatty/greasy film with blood; c) white amorphous residue (cf. bone) smeared perpendicular/ diagonal to edge; d) blood residue with “mud-cracked” appearance; e) collagen residue stained with Orange G, transmitted light.
Fig 7.
Residues on BT25 (unused) as described during blind test.
a) Plant fibre on distal end of the ventral surface; b) unidentified, black tacky material (possible haft-residue) on ventral edge; c) sediment and organic fibres (cf. wood) occurring in an isolated region on the ventral surface, with evident directionality; d) starch grain and amorphous plant tissue removed from the same region as in c, along the edge on the ventral surface.
Fig 8.
Residues on BT19 (unused, deposited in river) as described during blind test.
a) Amorphous use-residue along Edge A, appearing as white translucent bundles of organic material; b) fatty animal collagen on unused edge; c) fish scale from the ventral proximal surface of the used edge; d) green algal spores, possibly contamination or part of the contents of the fish’s stomach; e) amorphous collagen tissue stained with Orange G.
Fig 9.
Residues identified on BT5 (unused, rolled in hide) as described during blind test.
a) White use-residue with evident directionality (diagonal from edge) along the ventral used edge; b) unidentified solidified brown residue from the proximal surface, probably contamination; c) unidentified organic tissue along the ventral used edge.
Table 7.
Summary of staining results per category of artefacts (False positive: something was stained that was not directly related to use, but to production, hafting or contamination; correct negative: no presence of the residue was correctly indicated).
Analyst 3 did not apply staining.
Table 8.
Summary of results based on in situ observation (up to 180x) for the identification of tool use per category of used artefacts (percentages calculated based on pieces correctly identified as having been used per analyst in order not to accumulate errors made on another identification level).
Table 9.
Summary of results based on transmitted-light observation for the identification of tool use per category of used artefacts (percentages calculated based on pieces correctly identified as having been used per analyst in order not to accumulate errors made on another identification level).
Fig 10.
Re-evaluation of residue presence on BT15 (perforating antler) by comparison with experimental reference.
a) Distal tip of BT15, used to groove antler for 25 minutes (50x); b) distal tip of exp. 69/06, used to groove antler for 30 minutes (50x). The tip of BT15 shows very few residue fragments in comparison to exp. 69/06, which is a consequence of the cleaning protocol.
Fig 11.
Residues identified on BT15 (perforating antler) as described during blind test.
a) White, translucent, amorphous residue on artefact edge, possibly from use; b) yellow mineral residues, probably from incidental contact (non-use residue); c-d) plant tissue and cellulose fibre from tool surface, probably contamination; e) starch grain and cellulose fibres from extracted residue material sampled along the proximal right edge, transmitted light.
Fig 12.
Use-residues identified on BT9 (scraping wood) as described during blind test.
a-c) Woody fibres along tool edge, acquired during use; d) plant material from residue extraction, stained with Methylene Blue to confirm plant origin.
Fig 13.
Use- and haft-residues on BT20 (processing tubers) as described during blind test.
a-c) Macroscopically visible plant and wood fibres present at various locations across the artefact surface, including the used edge; d) plant residue with distinctive cell structure, present on the possibly hafted end of the tool; e) plant fibres and woody tissue on the non-used edge of the tool, artefact surface; f) bundles of starch grains removed from the working edge of the tool and photographed under transmitted light: left image in part-polarised light and right image in cross-polarised light to show distinctive extinction crosses.
Table 10.
Summary of results based on in situ observations (up to 180x) for the identification of used edge per category of used artefacts (percentages calculated based on pieces correctly identified as having been used per analyst in order not to accumulate errors made on another identification level).
Partially correct means that when both edges were used only one was identified.
Fig 14.
Residues identified on BT3 (processing fish) as described during blind test.
a) Fish scale on the ventral surface of the flake, acquired during use; b) possible dried fish collagen, also on the ventral surface; acquired during use; c) fatty and greasy use residues (cf. blood and collagen), acquired during use; d) unidentified green fibre, possibly grass, with a fish scale beneath it.
Table 11.
Summary of results based on in situ observations (up to 180x) for the identification of prehensile mode per category of artefacts.
Table 12.
Summary of results based on in situ observations (up to 180x) of the prehensile mode for the unused and non-hafted artefacts.
Table 13.
Summary of results based on transmitted-light observations of extracted residues for the identification of the prehensile mode per category of artefacts.
Fig 15.
Use- and haft-residues identified on Blind Test Tool 13 as described during blind test (a-d) and during re-examination (e).
a-b) Striated muscle tissue, blood and collagen residues on tool edges; c) hair fibre (cf. horse or deer) imbedded in muscle tissue on used edge, ventral surface; d) woody fibres possibly from hafting, dorsal surface; e) collagen fibre (not wood) after extraction during re-examination.