Monkey Reject Unequal Pay PDF

Cognitive Ethology Brosnan & de Waal (2003) - Monkey reject unequal pay ❖ One theory proposes that aversion to inequity can explain human cooperation within the bounds of the rational choice model and may be more inclusive than previous explanations ❖ ‘Sense of fairness’ is a human uni...

Cognitive Ethology Brosnan & de Waal (2003) - Monkey reject unequal pay ❖ One theory proposes that aversion to inequity can explain human cooperation within the bounds of the rational choice model and may be more inclusive than previous explanations ❖ ‘Sense of fairness’ is a human universal that has shown to prevail in a wide variety of circumstances ❖ Inequity aversion may not be unique to humans as not the only social animals ❖ Many highly cooperative nonhuman species seem guided by a set of expectations about the outcome of cooperation and the division of resources ❖ Brown capuchin monkey responds negatively to unequal reward distribution in exchanges with a human experimenter ❖ Monkeys refused to participate if they witnessed a conspecific obtain a more attractive reward for equal effort, an effect amplified if the partner received such a reward without any effort at all These reactions support an early evolutionary origin of inequity aversion ❖ Two conditions were used: ‘Equality’ → two monkeys exchanged tokens with a human experimenter to receive cucumber ‘Inequality’ → one monkey exchanged for cucumber and its partner for grape (a more favoured food) ❖ Only females reacted differently in the two conditions Compared with equality tests, females receiving the less favoured reward in inequality tests were less willing to exchange, whereas males showed no such effect Independent evidence indicate capuchin females pay closer attention than males to the value of exchanged goods and services ❖ The study reported here concerns only five females, which were subjected to the equality and inequality conditions plus two new controls: ‘Effort controls’ → a grape was simply handed to the partner by the experimenter (no exchange) followed by the subject herself exchanging for cucumber ‘Food controls’ → in the absence of a partner, the subject witnessed a grape being placed in the location where the partner normally sat, after which the subject herself exchanged for cucumber. Measured the monkeys’ rate of and latency to successful exchange.  Available rewards were visible to both monkeys, but neither was shown which reward they would receive before successfully returning the token. Divided incomplete exchanges into two categories: (1) failure to hand back the token (no token, NT) (2) failure to accept or eat the proffered reward (reject reward, RR). Both kinds of incomplete exchanges often involved active rejection, such as tossing the token or reward out of the test chamber. ❖ Method For exchange, the subject was given a token that could immediately be returned to the experimenter for a food reward. The experimenter stood before the monkey with the left hand outstretched in a palm-up begging gesture and with the right hand in the laboratory coat pocket. No other cues were given to encourage the monkey, and no reward was shown before correct exchange. The monkey had 60 s to place the token into the palm of the experimenter’s outstretched hand. Throwing the token at the experimenter or out of the test chamber did not count as an exchange. After a successful return, the experimenter lifted the correct reward from a transparent bowl visible to both monkeys and gave it to the exchanger. In cases of failure to exchange, no reward was shown. Exchange interactions were typically completed in about 5 s, and all subjects exchanged successfully in 95% or more of the baseline tests. All subjects had at least 2 yr experience with the exchange scheme, but none had been used previously in any similar study. Friedman’s tests were used to compare individuals’ mean failure to exchange across test types, and pair-wise comparisons were conducted using Tukey’s multiple comparisons. When comparing exchange rate in the first and second half of tests, exact Wilcoxon signed ranks tests were used. All reported P-values are two-tailed. ❖ Capuchin monkeys, too, seem to measure reward in relative terms, comparing their own rewards with those available, and their own efforts with those of others. ❖ They respond negatively to previously acceptable rewards if a partner gets a better deal. ❖ These emotions, known as ‘passions’ by economists, guide human reactions to the efforts, gains, losses and attitudes of others  ❖ It has been proposed that nonhuman primates are guided by species-typical expectations “about the way in which oneself (or others) should be treated and how resources should be divided”. ❖ As opposed to primates marked by despotic hierarchies, tolerant species with well-developed food sharing and cooperation, such as capuchins may hold emotionally charged expectations about reward distribution and social exchange that lead them to dislike inequity. Massen et al. (2014) - Ravens notice dominance reversals among conspecifics within and outside their social group ❖ The ‘social brain hypothesis’ (SBH) attributes the evolution of intelligence to the cognitive demands of social life. ❖ In support of the SBH, measures of social complexity and/or competence are found to correlate with neocortex size and reproductive success. ❖ The type and quality of social relationships turns out to play a key role in several vertebrate societies, irrespective of group stability and the degree of fission–fusion dynamics. ❖ Species living with long-term pair partners, i.e, tend to have bigger brains than those forming short-term or seasonal relations. ❖ The exceptions are primates, possibly because their social life requires them to deal not only with one but several long-term relationships at a time. ❖ Primates not only recognize others as kin, friend or dominant but also understand third-party relationships within these kin-, friendship- and/or dominance networks. ❖ A similar picture has been discussed for spotted hyenas, which live under social conditions comparable to primates. ❖ Recently, the SBH has been extended to birds and used to explain the apparent case of convergent evolution of intelligence in apes and corvids. ❖ Although several bird species seem to be capable of transitive inference, only two species have been experimentally tested for using this capacity to predict their own dominance status compared with that of a stranger. Note that these inferences are based on recent events, that is, seeing others winning or losing against a known individual, and do not necessarily require knowledge about the relationship between the other individuals. ❖ The experiments clearly show that the birds readily used the experience they had with one of the combatants from previous encounters. ❖ As the largest and most widely distributed member of the corvid family, ravens are renowned for their relatively big brains and high behavioural and ecological flexibility. ❖ Their cognitive skills are expressed primarily in the social domain: they flexibly switch between group foraging (including active recruitment) and individual strategies (like providing no or false information about food, attributing perception and knowledge states about food caches to others) But they form and maintain affiliate social relations aside from reproduction and engage in primate-like social strategies like support during conflicts, and reconciliation and consolation after conflicts. ❖ Ravens also remember former group members and their relationship valence over years, which might be important for life in non-breeder flocks where some individuals stay together over extended periods of time, whereas others do not. ❖ A consequence of these dynamics is that ravens regularly meet conspecifics of different degrees of familiarity, many of which they have never interacted with before. ❖ As dominance rank heavily depends on affiliation status and social support by others, raven non-breeders are ideal to test for the ability of third-party understanding between birds that regularly interact but also of those that know each other merely by observation. ❖ We tested 16 captive common ravens on their ability to recognize third-party rank relations of individuals they regularly interact with (group members) and those they do not (neighbouring group) by use of a playback experiment applying an expectancy violation paradigm. ❖ Methods Experiments started after all birds were comfortable with a short individual separation in the middle compartment B, while their conspecifics remained in parts A and C. For testing, the focal subject was called either into subdivision B-I or B-II, that is, in the half being closer to A or C, respectively; the loudspeaker used for playing back the stimuli was hidden in the opposite subdivision, always behind the wooden hut. Specifically, the loudspeakers’ position was such that the direction of the played back stimuli was congruent with the current position of the group that particular stimuli could come from: if the focal subject was positioned in B-I, it was tested with stimuli of group 1 from the direction of C; if it was positioned in B-II, it was tested with stimuli of group 2 from the direction of A. Each playback contained three vocal interactions of the same individuals, each separated by 1 min. Loudness was adjusted to the natural submissive vocalisation sound pressure levels. The actual playback loudness at the receiver varied depending on the focal bird’s position in the aviary and the weather conditions.  To hinder social learning and/or disruption of established hierarchies, the test playbacks were masked for all other animals using synchronised white-noise playbacks from two loudspeakers one directed at each group. All loudspeakers were visually occluded for all animals. The playback consisted of two types of vocalisations: Self-aggrandizing display (hereafter SAD) Submissive calls. Ravens of both sexes show SADs accompanied by a dominant posture, as a directed dominance display, which is often followed by submissive calls, and submissive posture and retreat by the subordinate individual. Note that the combination of SADs and submissive calls determined the meaning of the interaction, that is, a mild conflict with clear outcome. Ravens can show SADs also in a non-directional way, typically when they have temporarily left or are about to join the group. Acoustically, SADs can be highly variable between regions and individuals and a single individual may produce several distinct SAD types (personal observation). In our case, most birds within each group shared their vocal display repertoire regardless of their sex but varied in the frequency of certain SAD type usage. To create the stimuli, we used the two predominant SAD types from each group. Each stimulus approximated a dyadic interaction of a dominant (SAD vocalisation) and subordinate (submissive vocalisation) individual. Only within-sex interactions were considered. All calls were recorded with a Sennheiser K6/ME66 shotgun microphone connected to a Marantz PMD660/Zoom H4n digital recorder or a Canon LEGRIA HD- camcorder. Best quality recordings were individually extracted, high-pass filtered at 200 Hz and peak amplitude normalised. SADs were normalised at 10 dB levels of the submissive calls to approximate the natural loudness difference between the two call types. Submissive calls are usually produced in bouts, which include adjacent calls without pause. For better approximation of the natural call occurrence, submissive calls were extracted singly or as two immediately adjacent calls. Dominance order was calculated using Landau’s linearity indices  Spearman’s rho-correlations was used to calculate inter-rater reliability regarding durational behaviours Principal component analysis to reduce amount of response variables Generalised linear mixed model used to assess the effect of condition, sex of the subject, sex of the playback, and age on the delta score ❖ Results reveal ravens show different behaviour after playbacks that simulate a rank reversal in their group in comparison with playbacks that suggest dominance interactions in line with the current dominance hierarchy. ❖ Ravens, just like primates, can distinguish these different types of playbacks and thus have some knowledge about the rank relations of their group members. ❖ Male ravens responded to playbacks violating the dominance relations of their neighbouring group. ❖ Ravens are capable of forming representations of others’ relationships that are entirely based on observation of other’s interactions. ❖ The subjects’ own ranks were independent of the ranks of the out-group members being played back, and the rank relations of out-group members could not be deduced through comparison of the absolute rank differences between the played back individuals and the tested individual (that is, the focal subject’s own rank relative to those of others). ❖ The different response patterns to in- and out- group members indicate that the played back stimuli were meaningful to the birds. All ravens tended to react with an increase in ‘stress’ behaviour, and particularly females reacted with an increase in self-directed behaviours, which often correlates with the reduction of stress, to simulated rank reversals in their own group. ❖ All ravens increased activity levels when the simulated rank reversal was about members of their own sex, that is, when it concerned the position close to their own in the rank hierarchy. ❖ (simulated) rank reversals in their own group seem stressful for ravens, especially when these reversals happen in positions close to your own rank (same sex) or when you are low in the dominance rank hierarchy. ❖ When the playback concerned simulated rank reversals in the neighbouring group, they showed no signs of stress or activity but a change in vocalisation and attention. ❖ They decreased these behaviours during violations, suggesting that they were prone to display interest in simulated interactions of known rather than unknown outcome. ❖ A sophisticated use of bystander information has also been found in the context of food caching, including judging the others’ perspectives and possibly even knowledge states. Krupenye et al. (2016) - Great apes anticipate that other individuals will act according to false beliefs ❖ Central to everything that makes us human (including our distinctive modes of communication, cooperation, and culture) is our theory of mind (TOM) ❖ TOM → ability to impute unobservable mental states, i.e desires and beliefs to others ❖ A variety of nonverbal behavioural experiments have provided evidence that apes can predict others’ behaviour, not simply based on external cues but rather on an understanding of others’ goals, perception and knowledge ❖ Unclear whether apes can comprehend reality-incongruent mental states (i.e false beliefs), as apes have failed to make explicit behavioural choices that reflect false-belief understanding in several food-choice tasks ❖ False-beliefs requires recognising that others’ actions are driven not by reality but by their beliefs about reality, even when those beliefs are false ❖ In human developmental studies, it is only after age 4 that children pass traditional false-belief tests, in which they must explicitly predict a mistaken agent’s future actions. ❖ Recent evidence has shown that even young infants can pass modified false-belief tests that involve the use of simplified task procedures and spontaneous-gaze responses as measures (i.e., violation of expectation, anticipatory looking). i.e, anticipatory looking paradigms exploit individuals’ tendency to look to a location in anticipation of an impending event and thus can measure a participant’s predictions about what an agent is about to do, even when that agent holds a false belief about the situation. ❖ Only two studies have used spontaneous-gaze false-belief tasks with nonhuman primates. Both failed to replicate with monkeys the results with infants, despite monkeys’ success in true-belief conditions. ❖ In our study, we used an anticipatory looking measure to test for false-belief understanding in three species of apes (chimpanzees; bonobos; orangutans). ❖ Previous studies have established that apes reliably make anticipatory looks based on agents' goal-directed actions and subjects' event memories. ❖ In our experiments, apes watched short videos on a monitor while their gaze was noninvasively recorded using an infrared eye-tracker. ❖ Our design, controls, and general procedure replicated a seminal anticipatory looking false-belief study with human infants. ❖ We conducted a pair of experiments using the same design but introduced distinct scenarios in each. ❖ The common design involved two familiarisation trials followed by a single test trial (either the FBI or FB2 (false belief one or two) condition; between-subjects design) (1) the agent witnessed the hiding of the object in one location before searching for it there. (2) the object was hidden in another location and the agent pursued it there. ❖ In our scenarios, a human agent pursued a goal object that was hidden in one of two locations. ❖ These trials served to demonstrate that the object could be hidden in either of the two locations and that, when knowledgeable, the agent would search for it in its true location. ❖ During the belief-induction phase, the agent witnessed the initial hiding of the object, but the object was then moved to a second location while the agent was either present (FB1) or absent (FB2). ❖ In both conditions, the object was then completely removed before the agent returned to search for it. ❖ The actions presented during the induction phase controlled for several low-level cues—namely, that participants could not solve the task by simply expecting the agent to search in the first or last location where the object was hidden or the last location where the agent attended. ❖ Whether the object was hidden first in the left or right location during familiarisation trials and whether the target of the agent’s false belief was the left or right location during test trials were counterbalanced across subjects. ❖ Experiments one and two presented scenarios that were specifically intended to evoke apes’ spontaneous action anticipation in different contexts. ❖ To encourage subjects’ engagement, we presented simulated agonistic encounters between a human (actor) and King Kong (KK), an unreal apelike character unfamiliar to the subjects. ❖ To minimise the possibility that apes could solve the task by responding to learned behavioural cues, our scenarios involved events that were novel to our participants. In experiment one, the actor attempted to search for KK, who had hidden himself in one of two large haystacks In experiment two, the actor attempted to retrieve a stone that KK had stolen and hidden in one of two boxes. We confirmed that apes unambiguously attended to the depicted actions during the belief-induction phases of both experiments. ❖ Apes’ anticipatory looks were assessed on the basis of their first looks to the target (the location where the actor falsely believed the object to be) or the distractor (the other location) as the actor  ambiguously approached the two locations—from the start to the end of the actor’s walk toward the haystacks ❖ Our findings show that apes accurately anticipated the goal-directed behaviour of an agent who held a false belief. ❖ Design and results controlled for several explanations. (1) apes could not solve the task by simply expecting the actor to search in the first or last location where the object was hidden, the last location the actor attended, or the last location KK acted on. (2) apes could not merely respond to violations of three-way associations between the actor, the target object, and the object’s location, formed during familiarisation or belief-induction phases. Instead, the apes actively predicted the actor’s behaviour. Heyes argued that a low-level account could explain Southgate et al.’s results if subjects overlooked the object’s movement while the agent was not attending and imagined the object in its previous location. We confirmed that apes closely tracked all such movements. (3) our results cannot be explained as attribution of ignorance rather than false belief. Apes did not simply expect the actor’s ignorance to lead to error or uncertainty; they specifically anticipated that the actor would search for the object where he falsely believed it to be. ❖ Apes were never shown the actor’s search behaviour when he held a false belief, precluding reliance on external behavioural cues learned during the task. ❖ By requiring subjects to make predictions in situations that involved a constellation of novel features (i.e., a human attacking an apelike character hiding in a haystack), we also minimised the possibility that subjects could apply behaviour rules acquired through extensive learning during past experiences. ❖ Acknowledge that all change-of-location false-belief tasks are, in principle, open to an abstract behaviour rule–based explanation—namely, that apes could solve the task by relying on a rule that agents search for things where they last saw them. ❖ This explanatory framework cannot easily accommodate the diversity of existing evidence for ape TOM nor can it account for recent evidence that human infants and apes appear to infer whether others can see through objects that look opaque, based on their own experience with the occlusive properties (i.e., see-through or opaque) of those objects.  ❖ Given that apes have not yet succeeded on tasks that measure false-belief understanding based on explicit behavioural choices, the present evidence may constitute an implicit understanding of belief. ❖ Differential performance between tasks may reflect differences in task demands or context, or less flexible abilities in apes compared with humans. ❖ At minimum, apes can anticipate that an actor will pursue a goal object where he last saw it, even though the apes themselves know that it is no longer there. ❖ That great apes operate, at least on an implicit level, with an understanding of false beliefs suggests that this essential TOM skill is likely at least as old as humans’ last common ancestor with the other apes. Handouts ❖ Distraction behaviour plover: behaviour is functional → fox is not near nest (example of plover distracting fox by playing as if they are wounded somewhere away from the nest) → what guides behaviour? ❖ Intentionality: Zero intentionality Internal and external stimuli determine behaviour Example: plover reacts with distraction behaviour to presence of fox First order intentionality Actor knows effect of the behaviour on other Example: Plover knows effect distraction behaviour → fox follows and will be led away from the nest Second order intentionality Actor knows that other has knowledge Example: Plover knows what fox thinks of distraction behaviour → ‘nice food that is easy to catch’ = theory of mind ❖ Occam’s razor: all things being equal, the simplest solution tends to be the best one → can be useful in physical science but dangerous in biology → so it is rash to use simplicity and elegance as a guide in biological research ❖ Human: intentional ‘idiot savant’: our interpretation of plover behaviour → fox knows that I will be an easy catch due to my broken wing ❖ Achieving goal in woodlice: they need to move to humid place → do they have humid place as goal? → woodlice has a goal in mind → they adjust their movement to achieve the goal → no true → emergent distribution → yet ‘goal-achieving system’ ❖ Intention rats: To have intention Not passive control But active control Have a goal (e.g. location; food item) Intentional states: Idea that goal can be reached through action(s) Will to reach the goal Rats pressed bar for sugar more when there was no poison compared to when there was → with chain pull for pellet they pulled more when there was no poison, but later on they pulled more when there was poison ❖ Cognition: processing of and decisions on basis of incoming information Humans often considered most advanced (primate-) species because of → theory of mind (ToM) ToM: the capacity to understand that other individuals have a ‘mind’ What is ToM? One cognitive capacity Build from simpler capacities Composed of several different cognitive capacities → emergent property ◆ Example in animals: precursors to ToM → gaze following → follow ‘line of sight’, understand object of attention, Visual Perspective Taking (know what others can see) → ToM is knowing what other know, but also manipulating what other sees/knows Precursor to ToM → understanding target of attention  Example: long-tailed macaques → use social features in long-tailed macaques → they have steep linear dominance hierarchies and aggression and submission that is unidirectional → we assume that they recognise the hierarchy of group members and recognise group members from pictures → females did not look longer at OM than neutral ones → males looked longer at OM than neutral ones so they might understand the target of attention of other individuals How is it expressed? Self-recognition in mirror ◆ Example: behaviour of chimpanzees after access to mirror → first three days loads of social responses afterwards more self-directed responses ◆ Example: mark-test → chimpanzees first did not touch mirror more if they were marked vs if not → when mirror was visible they only touched when they were marker ◆ Example: chimpanzees looked at themselves through a hand-held mirror ◆ Example: elephants → previous tests on elephants showed no self-recognition → but they used small mirror that was out of reach → so new test was conducted → looking at social reaction, search behind mirror, testing of mirror, self-directed behaviour → three elephants were tested and all show self-directed behaviour and only one individual passed the mark-test → does this mean self-recognition in elephants? ◆ Example: fish → lots of mouth-fighting in beginning when a mirror was placed, but then it is replaced by more frequency of the fish being close to the mirror → other case is that they only stay a bit close to the mirror but nothing happens (so they fail) → with other members they also just stay near the mirror and that is it → when provided with a coloured tag in a modified mark test, fish attempt to remove the mark by scraping their body in the presence of a mirror but show no response towards transparent marks or to coloured marks in the absence of a mirror False belief  ◆ Sally-Anne test → you have Sally and Anne → Sally put her ball in the basket and goes away → Anne moves ball to her box → where will Sally look for her ball? Example: children vs apes → a finding game where one adult (hider) hides a reward in one of the two identical containers and the other adult (communicator) tries to help the participant with finding the reward by marking the box where the reward is → the communicator placed the marker where she saw the reward hidden; the container that was at that location is now at the other location; so the reward is at the other location →results were that children’s performance on the verbal and nonverbal false belief tasks were highly correlated and no ape succeeded in nonverbal false belief task → great apes however did succeed (3 species of them) Gaze following ◆ Example: monkey looked more often up when demonstrator looked up than straight ◆ Example: long-tailed macaques → they were showed the faces of the actor (human) with different emotions → macaques look more often up when demonstrator has a social neutral facial expression → post-hoc → fear face gives significant difference Perspective taking ◆ Cognitive mechanism: Low level explanation → Mere response to movement of interaction partner, no understanding of the other’s visual target High level explanation → Understanding of the fact that the interaction partner is seeing something else Example: look around the barriers → all great apes do follow gaze of human experimenter even around barriers → also long-tailed macaques  Example: ape is trained to ask for food from human → then one human has the bottom half of the face covered and the other the top half → result shows that they can model visual perspectives of others Visual perspective: example of where monkeys had to request from human → human either stared at monkey or had her eyes closed or sat with back towards monkey or left the room → 2nd experiment the human either had their body and/or face oriented towards the subject → results are that monkeys produce more behaviours when watched, but they were sensitive to body and face orientation separately → so monkeys encode the information for the two separately → face orientation encode to observer’s perceptual access → body orientation encodes to observer’s disposition to transfer food Chimpanzees cannot do this → behaviour reading → they do not understand task → further research with tasks that animals understand Example: long-tailed macaque → competition for food → adaptations → one-way mirror for dominant (D) and screens at both food boxes for D → results the sub preferred the invisible item compared to the D Example: raven → they take into account the visual access of others, even when they cannot see a conspecific → ravens guard their caches against discovery in response to the sounds of conspecifics when a peephole is open but not when it is closed → ravens can infer the possibility of beings seen Deception ◆ Example: monkey grooming another monkey behind a rock → you only see one monkey but the groomee not → thus the monkey that looks at them is deceived as he only sees one of them and not both