Transitive inference in cleaner wrasses (Labroides dimidiatus)

Abstract

Transitive inference (TI) is the ability to infer unknown relationships from previous information. To test TI in non-human animals, transitive responding has been examined in a TI task where non-adjacent pairs were presented after premise pair training. Some mammals, birds and paper wasps can pass TI tasks. Although previous studies showed that some fish are capable of TI in the social context, it remains unclear whether fish can pass TI task. Here, we conducted a TI task in cleaner wrasses (Labroides dimidiatus), which interact with various client fishes and conspecifics. Because they make decisions based on previous direct and indirect interactions in the context of cleaning interactions, we predicted that the ability of TI is beneficial for cleaner fish. Four tested fish were trained with four pairs of visual stimuli in a 5-term series: A-B+, B-C+, C-D+, and D-E+ (plus and minus denote rewards and nonrewards, respectively). After training, a novel pair, BD (BD test), was presented wherein the fish chose D more frequently than B. In contrast, reinforcement history did not predict the choice D. Our results suggest that cleaner fish passed the TI task, similar to mammals and birds. Although the mechanism underlying transitive responding in cleaner fish remains unclear, this work contributes to understanding cognitive abilities in fish.

Further evidence for the capacity of mirror self-recognition in cleaner fish and the significance of ecologically relevant marks

“…This is a small fish, up to 15 cm in total length (TL), of protogynous hermaphrodite, changing sex from female to male, and they have harem polygynous mating system [ 50 , 51 ]. This fish is a model species for the study of fish cognition [ 52 – 54 ], and many aspects of fish social cognitive capacities have been reported from this fish, for example, the strategic use of tactical deception [ 55 ], transitive inference [ 56 ], a strong ability to delay gratification [ 57 ], a base for theory of mind [ 43 ], and MSR [ 25 ].…”

“…To examine whether the pass rate of this fish species was so high because our stimulus was of high ecological relevance, we used blue and green VIE marking, which do not resemble ectoparasites ( Fig 1B ). Cleaner fish distinguish a variety of color including blue and green [ 56 ]. We avoided the colors of red, orange, or yellow, which are different from brown but more or less similar to parasite.…”

Positional inference in rhesus macaques

“…Although the scope and sophistication of serial learning varies, some form has been reported in every vertebrate species that has been tested . Recently, fish (Hotta et al, 2020) and wasps (Tibbetts et al, 2019) have displayed evidence of being able to not only learn arbitrarily ordered sequences of discriminable colors, but to also exploit that knowledge to make transitive inferences about novel stimulus pairings. For example, wasps trained to favor red over blue, as well as blue over yellow, were given a choice between red and yellow.…”

No evidence for general intelligence in a fish

“…It is important to note that a more modular organisation of the brain does apparently not prevent the emergence of complex cognitive processes like transitive inference, generalised rule learning and even mirror self‐recognition (Grosenick et al, 2007; Hotta et al, 2020; Kohda et al, 2019; Wismer et al, 2016), i.e. processes that go beyond conditioning.…”

“…Fish do many apparently smart things (Brown, 2015; Bshary et al, 2014; Salena et al, 2021; Vila Pouca & Brown, 2017), often based on cognitive processes that are considered to be more complex than Pavlovian and operant conditioning. To give a few examples, fish use cognitive maps (Reese, 1989), payoff‐based social learning rules (Brown & Laland, 2003; Kendal et al, 2009; Street & Laland, 2016; Truskanov et al, 2020; Vila Pouca et al, 2020), generalised rule learning (Wismer et al, 2016), or transitive inference (Hotta et al, 2020) and show evidence for mirror self‐recognition (Kohda et al, 2019), some basic perspective‐taking (McAuliffe et al, 2021), prosocial behaviour (Satoh et al, 2021), and counting abilities and the ability to delay gratification that match the performance of primates (Aellen et al, 2021; Triki & Bshary, 2017). Yet, being ectotherm vertebrates, they have on average ten times smaller brains corrected for body size compared to endotherm vertebrates (Jerison, 1973; Tsuboi et al, 2018).…”