False memories in cuttlefish.

Episodic memory is a reconstructive process per se: during an event, the features composing it are encoded and stored separately in the brain, then reconstructed when the event's memory is retrieved. Even with source monitoring processes (e.g., did I see or did I smell it?), some mistakes can occur. These mnemonic mistakes happen especially when different events share several features, producing overlaps difficult to discriminate, leading to the creation of false memories. The common cuttlefish has the ability to remember specific events about what happened where and when, namely episodic-like memory. In order to investigate whether this memory, such as human episodic memory, is based on reconstructive processes, we elaborated a protocol promoting false memory formation. Our results suggest that cuttlefish do form visual false memories, but not olfactory false memories. These memory errors might be the first indication of the presence of reconstructive processes in the memory of cephalopods.

Unruly octopuses are the rule: Octopus vulgaris use multiple and individually variable strategies in an episodic-like memory task.

Episodic-like memory has mainly been studied through experimental tasks in which subjects have to remember what they ate, where and when or in which context. Seemingly quite common in mammals and corvids, episodic-like memory ability has also been demonstrated in the common cuttlefish, a cephalopod mollusc. To explore whether this ability is common to all cephalopods or whether it has emerged to face specific ecological constraints, we conducted an episodic-like memory task with seven Octopus vulgaris. Only one individual learnt the replenishing rates during training and subsequently showed episodic-like memory ability, whereas the other individuals favoured simpler foraging strategies, such as avoidance of familiarity and alternation, use of a win-stay strategy and risk sensitivity. A high variability in the use of these strategies was observed between and within individuals throughout training. As octopuses seem to live under lighter environmental pressure than cuttlefish, they may not need to rely on episodic-like memory ability to optimize foraging as cuttlefish do. These results highlight the differences in the use of complex cognitive abilities between cuttlefish and octopuses, which might be linked to different environmental and predatory constraints.

Dogs fail to reciprocate the receipt of food from a human in a food-giving task.

Domestic dogs have been shown to reciprocate help received from conspecifics in food-giving tasks. However, it is not yet known whether dogs also reciprocate help received from humans. Here, we investigated whether dogs reciprocate the receipt of food from humans. In an experience phase, subjects encountered a helpful human who provided them with food by activating a food dispenser, and an unhelpful human who did not provide them with food. Subjects later had the opportunity to return food to each human type, in a test phase, via the same mechanism. In addition, a free interaction session was conducted in which the subject was free to interact with its owner and with whichever human partner it had encountered on that day. Two studies were carried out, which differed in the complexity of the experience phase and the time lag between the experience phase and test phase. Subjects did not reciprocate the receipt of food in either study. Furthermore, no difference was observed in the duration subjects spent in proximity to, or the latency to approach, the two human partners. Although our results suggest that dogs do not reciprocate help received from humans, they also suggest that the dogs did not recognize the cooperative or uncooperative act of the humans during the experience phase. It is plausible that aspects of the experimental design hindered the emergence of any potential reciprocity. However, it is also possible that dogs are simply not prosocial towards humans in food-giving contexts.