Data from: Wild recognition: Conducting the mark test for mirror self-recognition on wild baboons
Data files
Dec 05, 2024 version files 29.76 KB
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Ahmad_et_al_wild_recognition_baboon_mirror_test_data.txt
20.82 KB
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r_script_wild_recognition_mirror_test.R
6.68 KB
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README.md
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Abstract
The distribution of self-awareness across species is important to understand, not only as a matter of scientific interest but because of its implications for the ethical standing of non-human animals. The prevailing methodology for determining self-awareness is to test for visual self-recognition using mirror-image stimulation and a ‘mark test’. However, most studies have involved very small sample sizes, omitted a control condition, and been conducted on captive animals. Here, we designed and implemented the first controlled mark test in a wild setting, conducting the mark test using a laser pointer on a large (N = 51 individuals, 135 mark tests) sample of wild chacma baboons (Papio ursinus) in situ. Control tests showed that baboons were interested in the mark, but this interest decreased with age, and was greater in males and towards green (cf. red) marks. However, as predicted, subjects showed no evidence of visual self-recognition, which, given the control, cannot be attributed to lack of motivation in the mark. Our study proposes a novel, controlled mark test in situ and contributes to the evidence that, without extensive training, non-hominid primates are not capable of full visual self-recognition.
README: Wild Recognition: Conducting the Mark Test for Mirror Self-Recognition on Wild Baboons
https://doi.org/10.5061/dryad.g79cnp601
Description of the data and file structure
We designed and implemented the first controlled mark test in a wild setting, conducting the mark test using a laser pointer on a large and heterogeneous sample of wild chacma baboons (Papio ursinus) in situ.
Files and variables
File: r_script_wild_recognition_mirror_test.R
Description: R code used to analyse the data and generate the figures for the publication.
File: Ahmad_et_al_wild_recognition_baboon_mirror_test_data.txt
Description: Data collected and analysed in the wild baboon mirror test paper
Variables
- id: a code indicating the identity of the individual
- date: numeric date that the test was completed
- test: 3 levels, 1, 2, 3: 1 = test condition in front of mirror; 2 = non-visible control; the laser is on a non-visible body part with no mirror present; 3 = visible control
- atleast_one: binary. 0 = no touches, 1 = at least one touch
- atleast_one_mouth: binary. 0 = no mouthing, 1 = at least one mouthing
- touch_number: number of touches of the mark
- male: sex 0 = female, 1 = male
- age: numeric, age in years
- colour_red: laser colour; 0 = green, 1 = red
- troop_n: code of the troop
- rank_relative: relative rank of the individual tested
- time_day: quartile of day testing was conducted. 1 = 6-9 AM; 2 = 9 AM-12 PM; 3 = 12-3 PM; 4 = 3-6 PM
- prior_laser_cat: category of prior laser exposure: 4 possible values (zero, lower, middle, and upper terciles; 0, 1, 2, 3)
- prior_mirror_cat: category of prior mirror exposure: 4 possible values (zero, lower, middle, and upper terciles; 0, 1, 2, 3)
- test_number: numeric count of test number in order
- repeatability_touch_number: number of touches counted by a second coder
- time_tested: duration of test (s)
- mouth_touches: count of the number of mouthing events of the mark
- tot_touches: count of the total number of touches (including mouthing and hand touches) of the mark
NA = no data
Code/software
Data analysis:
Data were analysed in R v3.6.0 using the lme4 and car libraries.
Methods
The experiment was conducted from May to October 2021 at Tsaobis Nature Park (15° 45’E, 22° 23’S), Namibia. Baboon dominance ranks were calculated using the I&SI method from dominance interactions recorded ad libitum by all members of the field team. Subjects’ linear ranks were converted to a relative rank using the formula 1−[(1−r)/(1−n)] where r is the individual’s absolute rank and n is the group size. Age was calculated to the nearest year based either on known birth dates, or estimated from data on patterns of females’ ovulation or individuals’ dental eruption.
Mirror exposure
Baboons the opportunity to learn about the reflective surface of a mirror. Two medium-sized (approx. 50 x 50 cm) Perspex-backed safety mirrors were placed near frequented water points. Holes were drilled through the corners of the mirrors, and the mirrors were then attached using fencing wire to a metal frame approx. 30 cm from the ground (Fig 1). This height allowed an average adult female to view her face when seated in front of the mirror. The frame was fastened securely to a metal pole or a tree using fencing wire. Individuals had physical access to the mirrors from all sides and were able to explore them together with others.
To track subjects’ mirror exposure, a motion-sensor video camera trap (Bushnell Natureview Essential HD Camera) was attached to a tree near a mirror, approximately 1 m from the ground. The camera was aimed to capture the mirror and any individual in front of it and was triggered by motion to record for 60 s during the day and 15 s at night (when baboons were not present) with a 1 s interval between videos. Video resolution was set to 1920 x 1080 px. Batteries were changed every three days.
Mark tests
From 19 June to 1 October 2021, individuals were subjected to the mark test, which included three test conditions: ‘visible control’, ‘non-visible control’ and ‘mirror’, described below. Tests were conducted opportunistically by Esa Ahmad at a distance of 7-10 m when subjects were either resting or sitting in front of the mirror. All tests were video recorded with a handheld camera (FugiFilm FinePix XP140 digital camera). Marks were applied using two colours: a green (532 nm) and a red (635 nm) laser pointer of output power 5 mw. Tests lasted for no more than 90 s, and usually less.
The visible test condition determined whether the subjects would investigate a mark visible on their own bodies. In this control condition, the mark was shone on a visible part of a subject’s body while the test subject was resting in absence of the mirror. The experimenter moved the laser slowly to ensure the subject was attending to it.The second control, the non-visible mark condition, was used to determine whether the laser mark could be felt by a subject and to establish a baseline rate of facial touching. In this condition, the experimenter shone the mark on a part of a baboon’s body that was not visible without a mirror, i.e. on the subject’s cheek or ear, when the subject was not facing a mirror. Finally, the test condition, the mirror mark test, determined whether the subject recognised its own face in the mirror. The mark was applied to the same ‘non-visible’ parts of a subject’s body, i.e. the cheek or ear, when the subject was looking into the mirror. If the subject was not looking in the mirror, the mark was removed. As in the visible condition, the mark was moved slowly to increase its salience.
For each presentation, a video coder recorded the following information: the (1) test subject’s identity, age (in years), sex, relative rank and troop; (2) test condition; (3) number of mark-directed touches; and, as control variables, the (4) test duration; (5) mark colour; (6) laser exposure; (7) total prior laser exposure of the subject; and (8) total prior mirror exposure of the subject. Prior mirror exposure was calculated from the camera trap footage. Where test duration was under 2 s, tests were excluded from the final dataset since such a short test did not contribute meaningfully to an individual’s mark exposure.
A mark-directed touch was defined as a clean, precise, and direct touch of the mark. Under the non-visible condition, test duration included all time when the mark was shone on a subject’s body. Under the mirror condition, test duration included only the time during which the subject could view the mark on his/her body i.e., when s/he was looking into the mirror.