Effect of demonstrator reliability and recency of last demonstration on acquisition of a socially transmitted food preference

Abstract

In the social transmission of food preference paradigm, naive observer rats acquire safety information about novel food sources in the environment through social interaction with a demonstrator rat that has recently eaten said food. Research into the behavioural mechanisms governing this form of learning has found that observers show increased reliance on socially acquired information when the state of the environment makes personal examination of their surroundings risky. We aimed to (1) determine whether reliance on social information would decrease if previous reliance on social learning was unsuccessful, and (2) whether reliance on the specific demonstrator that had transmitted poor information would similarly decrease. By inducing illness in observers following consumption of a socially demonstrated food, we created an environmental situation in which reliance on socially acquired information was maladaptive. We found that under these conditions, observers showed no change in their reliance on a specific demonstrator or socially learned information in general. Our experiment also unexpectedly produced results showing that recent demonstrators were more influential in later transmissions than demonstrators that had been learned from less recently. Notably, this effect only emerged when the observer simultaneously interacted with both demonstrators, indicating that demonstrators must be in direct competition for this effect to manifest.

Keywords: conditioned taste aversion; demonstrator reliability; food choice; social learning; social transmission of food preferences.

Figure 1.

Observers display a preference for a demonstrated novel flavour over an undemonstrated novel flavour. (a) Mean (±s.e.m) percent preference for a demonstrated flavour versus a novel flavour at a choice test following either a 15- or 30-min interaction with their demonstrator. Observers in the high interaction time (30 min) but not the low interaction time (15 min) condition displayed a significant preference for the demonstrated flavour. (b) The mean (±s.e.m.) total amount in grams eaten by observers during the choice test as a function of interaction time. Results indicate no effect of interaction time on food consumption (*p < 0.05).

Figure 2.

Experiment 2 behavioural procedure. The top flowchart lists housing details during the experiment and gives an abbreviated outline of the order of procedures. The graphics below display the specifics of the each procedure. In brief, observers acquired two STFPs through interaction with (a) demonstrator 1 (D1) followed by (b) interaction with demonstrator 2 (D2) 2 days later. After each interaction, observers were given access to the demonstrated flavour and then injected with either LiCl to induce illness and a conditioned taste aversion or Saline as a control. Rats that had demonstrated a flavour that was followed up with a LiCl injection were tagged as unreliable. (c) Two days following the second demonstration, observers were allowed to learn two new STFPs via simultaneous interaction with their demonstrators and then completed a choice test to determine whether they displayed increased reliance on information obtained from the reliable demonstrator. Following the end of the main experiment, observers were given a second choice test between the flavours which had been followed up with an injection to ensure that they had acquired a conditioned taste aversion to the LiCl paired flavour.

Figure 3.

Demonstrator reliability does not affect subsequent learning. (a) The mean (±s.e.m.) amount in grams consumed of diets demonstrated by unreliable demonstrators (red bar) versus reliable demonstrators (grey bar) in Experiment 2. Rats that had experienced an aversive outcome after consuming a food they had acquired an STFP for from the Unreliable demonstrator showed no change in their tendency to rely on new information obtained from that rat. (b) Experimental condition did not appear to affect the mean (±s.e.m.) total amount in grams eaten by observer rats at the STFP strength choice test. (c) The average preference of observers (±s.e.m.) for the demonstrated flavour that had later been followed up by a LiCl injection (white bar) as compared to the demonstrated flavour that had been followed up with a saline injection (blue bar) as assessed during the conditioned taste aversion verification choice test in Experiment 2. Results indicate that observers successfully acquired the taste aversion. (**p < 0.01).

Figure 4.

Relative recency of past STFP acquisition from a given demonstrator (i.e. demonstrator order) facilitates subsequent learning from that demonstrator. The average amount in grams (±s.e.m.) eaten of the demonstrated diets separated by (a) demonstrator reliability and order for observers in the LiCl-injected groups or (b) demonstrator order and injection condition. (c) The average duration in seconds (±s.e.m.) spent by observers socially attending to each demonstrator. We found no significant differences in observer-initiated social contact between the two demonstrators for any of the scored behaviours (**p < 0.01).

Figure 5.

Experiment 3 behavioural procedure. The top flowchart lists housing details during the experiment and gives an abbreviated outline of the order of procedures. The graphics below display the specifics of each procedure. (a) Observers interact with a demonstrator that has recently eaten anise-flavoured chow. Afterwards, they are given 1 h to eat anise chow and then injected with either LiCl to induce gastrointestinal distress or saline as a control. (b) Two days following this first demonstration, observers interact with either the demonstrator they learned from earlier OR a novel demonstrator after they have eaten cinnamon flavoured chow. Afterwards, observers are given a choice test between cinnamon chow and the novel cocoa flavoured chow. Following the end of the main experiment, observers were given a second choice test between anise chow and the novel flavoured marjoram chow to verify that LiCl-injected observers had acquired a conditioned taste aversion.

Figure 6.

Demonstrator novelty and past reliability do not affect subsequent learning in a between-subjects model. (a) The mean (±s.e.m.) preference of observers for the second flavour they received a demonstration for in Experiment 3 based on the novelty of the demonstrator and the injection they received following the first demonstration. (b) The mean total (±s.e.m.) amount in grams eaten by observers during the STFP strength choice test in Experiment 3. (c) Results of the conditioned taste aversion verification choice test on the final day. Observers made ill by LiCl injection following consumption of the demonstrated diet showed a significant aversion towards that diet (**p < 0.01).