Domestic pigs’ (Sus scrofa domestica) use of direct and indirect visual and auditory cues in an object choice task

Abstract

Recently, foraging strategies have been linked to the ability to use indirect visual information. More selective feeders should express a higher aversion against losses compared to non-selective feeders and should therefore be more prone to avoid empty food locations. To extend these findings, in this study, we present a series of studies investigating the use of direct and indirect visual and auditory information by an omnivorous but selective feeder-the domestic pig. Subjects had to choose between two buckets, with only one containing a reward. Before making a choice, the subjects in Experiment 1 (N = 8) received full information regarding both the baited and non-baited location, either in a visual or auditory domain. In this experiment, the subjects were able to use visual but not auditory cues to infer the location of the reward spontaneously. Additionally, four individuals learned to use auditory cues after a period of training. In Experiment 2 (N = 8), the pigs were given different amounts of visual information about the content of the buckets-lifting either both of the buckets (full information), the baited bucket (direct information), the empty bucket (indirect information) or no bucket at all (no information). The subjects as a group were able to use direct and indirect visual cues. However, over the course of the experiment, the performance dropped to chance level when indirect information was provided. A final experiment (N = 3) provided preliminary results for pigs' use of indirect auditory information to infer the location of a reward. We conclude that pigs at a very young age are able to make decisions based on indirect information in the visual domain, whereas their performance in the use of indirect auditory information warrants further investigation.

Farm Animal Cognition—Linking Behavior, Welfare and Ethics

“…Although pigs could solve the tasks, it was unclear whether they simply relied on stimulus enhancement cues (i.e., the slope of the board and the shaking movement or noise of the cup). Nawroth and von Borell (24) repeated the latter task that used a shaking bucket with a modified setup. Here, pigs were tested in their ability to use indirect visual and auditory stimuli (i.e., the absence of visual or acoustic cues) by choosing between two potential hiding locations.…”

Feasibility of pooled oral fluid collection from pre-weaning piglets using cotton ropes

“…However, weaning at 21 days of age is common practice in most pig farming areas. The other strategy is inspired by the fact that pigs are known to be good learners, whether in trials associated with food delivery ( Gieling, Nordquist, & van der Staay, 2011 ) or through repetition ( Nawroth & von Borell, 2015 ). This strategy would use the pigs’ natural ability by ‘training’ them to interact with the rope.…”

Piglets Learn to Use Combined Human-Given Visual and Auditory Signals to Find a Hidden Reward in an Object Choice Task

“…We did not find learning patterns between test sessions, which corresponded to our expectation as we did not want piglets to learn but wanted to test their spontaneous behaviour. Nawroth and von Borell [45] reported that piglets needed up to 72 or 84 trials to reach the success criterion using visual or auditory signals respectively in the same sessions of a test. This large number of trials would be closer to a training process instead of simply testing pigs’ spontaneous inter-specific communicational capacities.…”

“…Olive baboons ( Papio anubis ) also performed begging gestures to obtain a reward from an experimenter even though they did not belong to the group trained to use this gesture. Piglets are known to be good learners in tasks associated with food delivery [44] and are able to learn through the course of experiments [45]. However, the spontaneous use of human pointing gestures and/or auditory signals reported in piglets, as well the effect of experience on their response still need attention.…”