Chimpanzees recognize their own delayed self-image

Abstract

Unlike mirror self-recognition, recognizing one's own image in delayed video footage may indicate the presence of a concept of self that extends across time and space. While humans typically show this ability around 4 years of age, it is unknown whether this capacity is found in non-human animals. In this study, chimpanzees performed a modified version of the mark test to investigate whether chimpanzees could remove stickers placed on the face and head while watching live and delayed video images. The results showed that three of five chimpanzees consistently removed the mark in delayed-viewing conditions, while they removed the stickers much less frequently in control video conditions which lacked a link to their current state. These findings suggest that chimpanzees, like human children at the age of 4 years and more, can comprehend temporal dissociation in their concept of self.

Cognitive Bias Modification for Behavior Change in Alcohol and Smoking Addiction: Bayesian Meta-Analysis of Individual Participant Data

“…The models for the cognitive bias and substance use outcomes were based on the hierarchical Bayesian t -test approach of Marsman et al ( 2017 ). We used the Bayesian t -test model formulation of Rouder et al ( 2009 ), assuming that the observations are normally distributed, and started with expressing the mean in the control condition of a particular study as and the mean in the training condition as , such that the difference in group means is equal to σδ .…”

“…In contrast to classical methods, which cannot distinguish between the absence of evidence (i.e., the data are uninformative) and the evidence of absence (i.e., the data support the null hypothesis H 0 ), Bayesian methods allow modeling and quantification of the evidence for each hypothesis, rather than relying on a dichotomous decision (Wagenmakers et al 2018 ). This is why we conducted the meta-analysis within the Bayesian framework, using a hierarchical random-effects modeling approach similar to that of Marsman et al ( 2017 ). In this approach, information about the effect can be estimated from the individual participants nested within individual studies – similar to the frequentist approach – but yielding posterior distributions for the effect sizes.…”

“…Further, the hierarchical structure of the group-level model shrinks individual results that are uncertain and relatively extreme to the group mean effect (Efron and Morris 1977 ; Lee and Wagenmakers 2014 ), and it is generally possible to obtain narrower posterior credible intervals since the uncertainty of the individual study effects are reduced by the information borrowed from other statistically similar studies. Finally, Bayesian hypothesis testing allows us to explicitly quantify the evidence in favor of the null hypothesis versus a specific alternative hypothesis (i.e., Bayes factor; Marsman et al 2017 ; Wagenmakers et al 2018 ).…”

Colour vision of green turtle (Chelonia mydas) hatchlings: do they still prefer blue under water?

“…Understanding the effects of rearing green turtles in different coloured tanks requires further experimentation. Furthermore, achromatic cues associated with colour targets could potentially influence the choice of colours by individuals ( Siniscalchi et al, 2017 ). While they found no evidence of achromatic cues influencing colour choices for domesticated dogs, this possibility cannot be excluded in the current turtle study.…”

Are chimpanzees “stuck” on their “selves” in video?

“…However, for reasons outlined below, the results of this research donotcompelthe conclusion thatchimpanzees recognize the continuity of self across space and time. Hirata et al (2017) covered chimpanzees in stickers on visible and invisible parts of their bodies (arms, faces, and heads). Across eight conditions, the chimpanzees viewed videos that showed their own image concurrently, their own image with minimal time delays (i.e., 1, 2, and 4 s), their own image with and without stickers frommorethanoneweekprior,andahumanbothwithandwithout stickers.…”