Sunday, 11 October 2015

Altruistic rats?



One of my favourite things is watching YouTube clips of claimed examples of animal altruism, i.e., animals demonstrating concern for the welfare of others, like this one which claims to portray a “quick-thinking” “hero pig” which “rescues [a] baby goat from drowning”.

 
  
Apart from being an interesting potential phenomenon in its own right, finding or not finding genuine examples of animal altruism might tell us something about human altruism. And if we discover altruism among certain animals, we might be able to study altruism in ways that would not be permitted with human research participants. Just imagine if we found that lab rats can be altruistic…

Right, that’s enough imagining. Let’s examine evidence.

A series of studies have been claimed to demonstrate altruism among rats. Two of the most recent have been Bartal, Decety, and Mason (2011) and Sato, Tan, Tate, and Okada (2015).

Bartal et al. (2011) “placed a free rat in an arena with a cagemate trapped in a restrainer. After several sessions, the free rat learned to intentionally and quickly open the restrainer and free the cagemate”. What is more, “when liberating a cagemate was pitted against chocolate contained within a second restrainer, rats opened both restrainers and typically shared the chocolate”. The researchers concluded that “rats behave pro-socially in response to a conspecific’s distress [thus] providing strong evidence for biological roots of empathically motivated helping behavior”. ‘“The bottom line,” Mason says, “is that helping an individual in distress is part of our biology”’ (Jabr, 2012).

This interpretation of Bartal et al.’s results received some criticism, with a particularly good example coming from Jentsch and Ringach (2011). The most important criticism is that rats are curious creatures which enjoy tight spaces and this may provide a more plausible explanation of Bartal et al.’s results than the one the original authors provided. This alternative runs roughly as follows. The rats’ curiosity motivated them to actively explore an interesting situation and thereby stumble upon the mechanism for opening the “restrainer”. They then quickly learned to do this deliberately and did so primarily so that they could explore the tight space of the “restrainer”. That is, the rats may not have been “liberating” “trapped” and “distressed” rats so much as learning how to access an area they wanted to explore. Two lines of evidence support this alternative explanation. One is that the “altruism motivated by empathy” explanation requires all manner of abilities that we have little reason to think rats have, whilst the alternative does not. The other is that the behaviour of the rats in the study seems somewhat inconsistent with the more dramatic interpretation but completely consistent with the alternative. In particular, one of the first thing that “liberating” rats do after “freeing” “trapped” rats is immediately go into the container, as can be seen within this video clip, the commentary of which should obviously be listened to critically:




Personally, I am far from convinced that this study provides strong evidence for “biological roots of empathically motivated helping behaviour” or that that “helping an individual in distress is part of our biology”. I am not even convinced that it provides compelling evidence that lab rats care in any way about the positive welfare of others.

In another series of studies, Sato et al. (2015) found that “rats quickly learned to liberate a soaked cagemate from the water area by opening the door to allow the trapped rat into a safe area”. Moreover, “in most test trials, rats chose to help the cagemate before obtaining a food reward, suggesting that the relative value of helping others is greater than the value of a food reward. These results suggest that rats can behave prosocially and that helper rats may be motivated by empathy-like feelings toward their distressed cagemate”.

Sound familiar?

Again we have the key behaviour of interest being described in terms of rats being motivated by a goal of improving another’s welfare. This is an incautious use of language. More objectively, rats learned to choose to operate a switch that had multiple effects. One of these was to open the door between separate compartments. This in turn allowed the soaked rats to move about in a bigger area, which involved them first getting out of the water. It also allowed the ‘rescuing’ (hereafter “dry”) rats access to a bigger area. It also allowed the soaked and the dry rats to have physical contact with each other. It may also have stopped the soaked rats making distressed, agitated, or demanding noises that may have irritated the dry rats. Etc. Crucial to interpreting the results of this study is deciding what the dry rats were trying to achieve by operating the switch.

Long story short, we don’t know. However, close examination of the evidence does not persuade me that the dry rats were motivated primarily by a goal of improving the welfare of the soaked rats. As with the Bartal et al. (2011) study, a more plausible and parsimonious explanation seems preferable. Until presented with evidence that persuades me otherwise, the best explanation of the Sato et al. (2015) results seems to run something like the following. Curious creatures that they are, dry rats were motivated to explore their surroundings, especially in the area that interesting (but not scary) noises were coming from, i.e., on the other side of the door where the soaked rat was. Exploration in this area resulted in the dry rats discovering that they could open the door which in turn had lots of positive consequences. One of these was access to a greater area to explore. Video evidence shows that one of the first things a dry rat did after opening the door was to stick its head into the area the soaked rat had ‘escaped’ from, a behaviour that the ‘rescued’ rat also subsequently engaged in. Data from Sato et al. (2015) is also strongly suggestive that when given free rein, all rats spent some time in the water, even when they started on dry land and this was true even for those rats which had hitherto started every experimental session as soaked rats. In short, dry rats were plausibly doing what they wanted to do and there is no reason to assume that what they wanted included improvements in another’s welfare.




If one wants to seek facts, there are dangers in both anthropomorphism and anthropodenial and both of these dangers are exacerbated by wanting one particular answer to the question of whether or not animals can display altruism. As far as I can tell, I am not motivated by anthropomorphism or anthropodenial desires. Based on reason and evidence, I do think that some animals can be altruistic. The most plausible explanation of the following video clip, for example, seems to me to be that one monkey is very much trying to improve the overall welfare of another, even if this means in the short term biting him, punching him, and dunking him in water. (If I am correct, this is an example of “superficial altruism”. Further evidence would be required to know why the monkey was trying to keep his companion alive.) 





I will consider potential altruism among other species on other occasions. I am not yet convinced, though, that it exists among rats.

That is my big conclusion for this post. I recommend that most of you stop reading now. Thanks for your attention and, as always, comments are welcome.

Oh, and sadly, the Hero Pig was apparently a fraud.


- - - - - - - - - - - -

A closer examination of Sato et al. (2015)


I am keen for students on my Psychology of Altruism course to develop their critical thinking. For them, critical thinking requires evaluating experimental findings and claims allegedly justified by them. For those students in particular, I include below an annotated email I have just sent to Nobuya Sato, the corresponding author for Sato et al. (2015). The email will make little or no sense to anyone who is not closely familiar with the details of the paper! I include it here to “show my working out” for the claims I make and the conclusions I reach above, to demonstrate what a hopefully objective, fine-grained critique looks like. Edit: Very soon after sending my questions, I received a comprehensive reply from Nobuya Sato. (Very impressive, Mr. Sato. Sincere thanks.) I report the reply to each question below almost verbatim, followed once again by commentary as the mood takes me. Enjoy! In case anyone is interested and left in any doubt, my mind has not been changed by the new information reported below.

Dear Nobuya Sato,

I very much enjoyed your recent paper in Animal Cognition entitled “Rats demonstrate helping behavior towards a soaked conspecific”. I used it in my teaching this week on a course called The Psychology of Altruism. It also features heavily in my blog post this week which is called Altruistic Rats? The latter can be found here: http://tomfarsides.blogspot.co.uk/2015/10/altruistic-rats?.html). In that blog post I include an annotated version of this email to you.

I am struggling to work out a few details from the paper and would be very grateful if you could answer some questions for me and/or correct my mistakes.

1.       Am I correct that you do not report how many rats opened the door on days 13-15 of Experiment 1, i.e., during the control conditions? If so, may I ask how many did open the door on each of these days? Also, if it was fewer than 10, did the same rats open or not open the door on each day? [Commentary: If most or all rats opened the door when there was no rat on the other side, as was the case on Days 13-15, how confident can we be that they are opening the door “to help a soaked rat”, even when there was in fact a rat to ‘save’? Knowing how many rats opened the door on particular days is also important to interpret latency times – see next question.]

"Yes, you are right. The number or rats opening the door was the same as that in door-opening sessions (9 rats). As you said, the same rats opened or not opened the door. I should have mentioned about that in our article." [Commentary: So, the same 9 rats which opened the door in the critical trials also opened the door on subsequent days when there was no rat in need of release on the other side. One possibility is that they had learned that there usually was a rat on the other side and they were opening the door just in case one was there and needed rescuing. Another is that they had learned that opening the door was rewarding for them personally and were continuing to open it for that reason. I think the latter more likely, which means that they were almost certainly opening the door when rats were on the other side for much the same reason.]

2.       Fig. 2, p. 1041 shows a latency of 300 seconds on Day 1 of Experiment 1. This suggests to me that all latency results are reported counting non-openers of the door as taking 300-seconds and being included in the averages (rather than latencies being the average for those rats which DID open the door). Am I correct on this, please? [Commentary: Interpretation of the latencies is very dependent on the answer to this question. To me, it would be more helpful to know the latency to first door-opening for those rats which opened the door. Otherwise, interpreting the shortening time over days as evidence of keenness to open the door (specifically among those which opened it) seems flawed. I return to this point in question 5 below.]

"Yes, you are correct."

3.       On Day 12 of Experiment 1, the latency looks to be 50 seconds in Fig 2b (p. 1041) and 20-seconds in Fig 3 (p. 1042). I assume this is because of imprecision in printing graphs. Could you please tell me what the latency on Day 12 was? [Commentary: If the latency on Day 12 was 50 seconds and Fig. 3 is corrected to accurately represent this, the data represented in Fig. 3 suggest that trained rats were opening the door more or less as quickly - as well as potentially with the same frequency – whether or not there was a soaked rat behind it.]

"The control test was carried out only in the rats that opened the door in the door-opening sessions. The data in Fig. 2b included the rat not open the door as 300 s." [Commentary: So, the rats who opened the door in the critical trials were slower to open it when there subsequently no soaked rat on the other side. As always, various interpretations are possible. I think my suspicion is that in the control conditions the rats were (a) not 'urgently' motivated to open the door by sounds from a rat on the other side of it, and (b) may have been wondering whether the absence of sounds on the other side of the door was anything to worry about. This is, of course, complete speculation. The fact remains that they did open the door, and not that much slower than before.]

4.       You report an Experiment 1 ANOVA main effect such that “soaked rats spent less time in the pool area than did the helper rats” (p. 1042). Figure 4 on the same page seems to indicate the opposite. Which was it, please, or have I misunderstood something? [Annotation: The key thing about Fig. 4 is raised in question 6 below. Finding apparent inconsistencies in a paper is always thought-provoking though, and this is the second one in quick succession.]

"You are right. We made the mistake in the text. I already published the erratum (http://​dx.​doi.​org/​10.​1007/​s10071-015-0906-9)." [Commentary: Sorry, gentle reader. I had seen about this erratum and had forgotten about it during my close analysis of the data in the paper. It is a shame that publishers do not amend online versions of paper within the paper, or at least make note of the erratum there. Nevertheless, the correction makes clear that these lab rats did voluntarily enter water and spend some time in it, which certainly makes me feel comfortable in my interpretation of the study's results. The more general lesson for my students is that you really should check the basis of every claim that is made, including mine.] 

5.       On p. 1042, you report an Experiment 1 ANOVA result as suggesting “that the helper rats in the role-reversal sessions … learned to open the door more rapidly than the helper rats in the door-opening sessions”. The difference in latencies that underlies this result seems to occur in part, though, because of different NUMBERS of rats opening the door in each case (with all door non-opening rats being given latency scores of 300-seconds). By the time at least 9 of 10 rats were helping, the latencies look very similar in each phase of the experiment. Does that seem a correct and fair assessment?

"As you said, we did ANOVA using all the rats' data. But, when we took out the data of the rat that did not open the door, the statistical results were not much different. Main effect of group: F(1,85) = 30.72, p < 0.0001. Main effect of session: F(5,85) = 21.91, p < 0.0001. Interaction: F(5,85) = 5.13, p < 0.0005" [Commentary. Good to know. Nevertheless, my point elsewhere remains valid. There were other potential reasons for the previously soaked rats to open the door faster than did the original dry rats. Indeed, the authors note this in the Discussion section of the paper.]

6.       A video I have found of part of the experiment (http://www.eurekalert.org/pub_releases/2015-05/s-ahp051215.php) shows an Experiment 3 rat very keen to get out of the water he or she was placed in. And various bits of data in your paper convincingly suggest that the rats have a strong preference to spend more time on ground than standing in water. However, the fact that all the rats in Experiment 1 spent at least about 30 seconds in the water (see Fig. 4, p. 1042) – even those placed on the ground with previous experience of being soaked – suggests that they may not always “avoid” water. And a quick internet search suggests the possibility that not all rats hate water. May I therefore ask: (a) Did rats in your experiments make signs of distress or agitation (e.g., via squeaking or body language) whenever they were in the water? (There is no sound on the video, unfortunately.) (b) Did those not in the water show any signs of distress or concern that may have stemmed from the situation the other rat was in? (c) Did those not in the water give any indication of offering sympathy or reassurance to those in the water?  (d) Did rats ever voluntarily get into the water (as would logically seem to have to be the case, given Fig. 4)? [Commentary: Interpretation of the results in this paper would be considerably enhanced had it been accompanied by data about the noises rats made and when, itself accompanied by the best-possible interpretation of what those noises (and other signals) usually signify in the species and strain of the animals used in this experiment. Given that the authors’ own interpretation of what was going on depends quite critically on claims about rats’ distress, it is curious that they make so little mention of any data indicative of such distress. And, as I say, the evidence that is available does not seem to me to be massively supportive of a “helping others’ in distress because I empathise with them and want to improve their subjectively-experienced welfare” sort of account. The following three questions all seek further data that might speak to these concerns. Finally, note that the video is of Experiment 3 which had much deeper water than was used in the first experiment.]

"I'm not sure what the sign of distress or agitation is. We did not record the sound with good quality. So, I can't answer this question precisely, but with my impression, the soaked rat spent longer time at the location close to the door. And, the helper rats often took a look at the cagemate.  It might be a sign of concern to the cagemate. The rats almost never got into the water. But, they sometimes put their upper half of the body into the water room (I guess this is because of rats' exploratory tendency), and got into the water by accident." [Commentary: Other researchers using rats report that distress is indicated by "considerable motor activity and loud, high-pitched squeaks” (Church, 1959, p. 132). Sato et al. cite distress as an important cause of the rats' behaviour in the study and it seems to be an important component of these researchers interpreting the rats' behaviour as they do. I note Mr. Sato's noting of rats' exploratory tendencies. The data showing the time the rats spent in the water when they had free rein makes it difficult for me to square this with them taking only accidental dips.]

7.       In the role-reversal stage of Experiment 1, did the (now) soaked rats make any noises or show any motions that might suggest that they were responding to their situation in different ways than did the originally soaked rats, e.g., with less distress, more expectation (of the hatch being opened), or similar?

"With my impression, they were not different. I'm not sure about the ultrasonic vocalization. If we record it, they might be different." [Commentary: Fair enough, on both counts. I am left unclear about how much noise and of what sort rats made at any time. And, of course, there may have been communication using ultrasound frequencies, pheromones, etc. We just don't know. Most importantly, we seem to have little evidence to judge the extent to which the rats were in and/or communicating distress.]

8.       In Experiment 2, did either rat show any sign of distress, or any indication of having any desire to get into the adjoining chamber?

"I did not notice the tendency. But, I think we have to be careful to make the conclusion. If we want to say about it, we have to define precisely what kind of behaviour the tendency is." [Commentary: On this we are in complete agreement. But I am left wondering, then, how so much of the paper was interpreted in terms of distress being present or absent, e.g., "In Experiment 2, the results indicated that rats did not open the door to a cagemate that was not distressed" (p. 1).]

9.       In Experiment 3 the pool water was deepened from 45 mm to 200 mm. Why? Did you have any concerns that the soaked rats in Experiment 1 might not be in distress?

"We concerned the difference in power of reinforcement when we make a comparison between the helping and food reward. But, now I don't think we need to use the deeper box in Experiment 3. In our recent experiments, we usually use about 50 mm deep."

10.    In Experiment 3 during the 10-day choice test period, did all “rescuer” rats open both doors during every trial, especially given that the criterion of them having been trained was that they previously opened the hatch “in 3 of 4 consecutive sessions” (within a minute) (p. 1044)? Please accept my apologies if the answer to this question is discernible from what you report in the paper but I could not be sure. [Commentary: This criterion surprised me. If one animal is keen to help another in distress, it seems odd to me that – other things being equal, as they were - it might do so only 3 out of every 4 times. More importantly, because only latency times are reported for Experiment 3 and those latencies might include any rats which did not open a particular door, confident interpretation of the latency data really requires knowing how many non-door-opening rats are included among any given reported figure. It is also worth noting that it took 20 days on average for rats to reach this criterion when there wasn’t a soaked rat on the other side of the door, i.e., when rewarded with chocolate. This is important because it suggests that the rats in Experiment 2 were simply not motivated enough to explore the door area and thereby discover that they could open it, especially when you remember that they had spent every hour of the last two weeks housed with the rat on the other side. This is a different interpretation than the one provided by the authors, which suggest that the rats typically don’t open the door in Experiment 2 because they only opened doors when rats on the other side are in distress.]

"I did not mention that in our article. I did not notice this. In the food trained rats, two rats did not open the cagemate door. One did not open the door in 1 trial of 10 test trials. The other in 3 trials of 10 test trials. In the helping trained rats, one rat did not open the food door. It did not open the door in 2 trials of 10 test trials. And, one different helping trained rat did not open the cagemate (trained) door in 1 trial of 10 test trials. We regarded the latency of not open trial as 600 s. Maybe, it should have mentioned in our article, too." [Commentary: Any student of mine who wants to discuss this part of the study needs to take these newly-discovered facts into account when interpreting the latencies in Experiment 3.]

Many thanks for any answers you may give to these answers. Thank you also for a very intriguing and stimulating paper.

With best wishes,

Tom



References

Bartal, I. B-A., Decety, J., & Mason, P. (2011). Empathy and pro-social behavior in rats. Science, 334 (6061), 1427-1430.
Jabr, F. (2012, May 7). Rats display altruism. Scientific American. Retrieved from http://www.scientificamerican.com/article/will-you-rat-me-out/
Jentsch, J. D., & Ringach, D. (2011, December 14). Empathy and altruism in rats. http://speakingofresearch.com/2011/12/14/empathy-and-altruism-in-rats/
Sato, N., Tan, L., Tate, K., & Okada, M. (2015). Rats demonstrate helping behavior toward a soaked conspecific. Animal Cognition, 1-9.


Image credits

Bartal rats: Link
Hero monkey: Link
Hero pig: Link
Hero pig fraud: Link
Sato rats: Link


How to cite this blog post using APA Style

T Farsides. (2015, October 11). Altruistic rats? Retrieved from  http://tomfarsides.blogspot.com/2015/10/altruistic-rats.html


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