SETI and the Meaningless Rio Scale


By John Traphagan, Trustee, METI International

An interesting question that often arises in relation to the search for extraterrestrial intelligence (SETI) is: What impact would contact actually have on humans? Several years ago, in an attempt to quantify the importance of candidate SETI signals we receive, astronomers Ivan Almar and Jill Tarter proposed a scale to measure social consequences of contact, based on the Torino Scale used to quantify the consequences of an asteroid approach to Earth by relating the likelihood of impact with potential damage the asteroid might cause.

The Rio Scale aims at quantifying social consequences of contact with extraterrestrial intelligence by relating three variables: discovery type, distance of origin, and type of phenomenon detected. Members of the IAA SETI Permanent Committee officially adopted the Rio Scale in 2002 and have continued to refine and “perfect” the scale, in order, according to the IAA website, to bring “some objectivity to the otherwise subjective interpretation of any claimed ETI detection.”

Unfortunately, the Rio Scale is a good example of what happens when attempts at social science are based on naïve and poorly conceived understandings of human behavior and society. In its current version, the scale assesses issues such as whether the signal originates nearby (in our solar system) or far away (another galaxy) or if it’s aimed directly at us or is a general beacon that we happen to intercept. The closer and more specific the signal, the more “important” on a scale of 0 (no importance) to 10 (extraordinary importance) the signal is in terms of social consequences.

Any social scientist looking at the Rio Scale would find numerous problems. First, the scale is meaningless because it attempts to quantify something in a universal way—the social significance of an event—that varies significantly depending on social variables such as race, gender, class, socio-economic status, ethnicity, etc. The list of social variables is long. It’s highly unlikely that all, or even most, people around the world would assign the same level of significance to the same type of contact incident.

Second, the scale isn’t based on scientific research—it’s little more than a nicely presented set of assumptions that have no grounding in empirical evidence. Thus, it’s entirely subjective, rather than objective. A good example can be found on the IAA website claim that the scale is necessary because, “a public announcement of a discovery of extraterrestrial intelligence would have societal consequences similar to the announcement of the impending impact of a large asteroid.” We have no evidence that this is true, particularly since we have never had an announcement of a large asteroid impact that was legitimate and perhaps the most significant evidence of widespread societal reactions to the announcement of extraterrestrial intelligence comes from the late 19th Century with Percival Lowell’s claims that there was an advanced civilization on Mars. That was a long time ago, and the social impact, despite the assumed civilization being right next door, was minimal and brief.

There is, in fact, no evidence that the variables presented, such as distance between Earth and the signal’s origin or whether we think the message was meant for us, would actually be important variables in how people react to the announcement. The variables in the scale are, themselves, highly subjective and based on assumptions rather than empirical data collected through systematic research.

Third, the scale is problematic from a data perspective, because it uses an ordinal scale to measure interval data.  The problem with this is that with interval data the distances between attributes have meaning, while with ordinal data they don’t.  Social scientists have understood for a long time that if you create a ranking scale, it’s difficult to determine what people actually mean when they rank attributes. For example, if I rank a group of ice cream flavors from 1 to 5, I might get something like this:

1. Chocolate

2. Mint chocolate chip

3. Vanilla

4. Strawberry

5. Squid Ink

The problem here is that I like 1 and 2 about the same amount, and 3 a little less. I don’t like Strawberry much, and I hate squid ink flavored ice cream (yes, I’ve had it). So, while the scale makes it look like the distances between variables are equal, in fact for me if I were to quantify the relationships here, the scale would look more like 1, 1.1, 1.2, 10, and 5,000. That would better reflect how I think about the flavors in terms of the consequences of eating them from a quantitative perspective. But, in truth, the relationship between these variables is a qualitative one and it doesn’t make much sense to try to quantify it, because the numerical values assigned to each flavor are arbitrary and would vary considerably form one person to another.

Because the authors apparently did no actual scientific research into how people might react to a contact announcement, the scale itself represents little more than their own assumptions. And those assumptions are based on weak understandings of human behavior and social organization. As a result, the scale is trivial and, were it to be used as a tool for creating “Rio values” to quantify estimates of the importance of any reported detection, the only thing it’s likely to accomplish is over-simplification and misrepresentation of the situation. Therefore, it will create a misleading estimate of any social consequences related to contact with ETI.  

A major goal for creating the scale was to communicate with the public. I’ve always thought it provides a false sense of certainty to something that’s largely guesswork.

The Rio Scale represents a fine example of what happens when people attempt to develop tools for measuring social phenomena on the basis of bad science—or in the case of the Rio Scale, no science at all. It’s an amateurish and misguided attempt at addressing important policy issues related to the social consequences, across complex human groups, of contact with extraterrestrial intelligence. As a result, it trivializes the social consequences of a very complicated potential event in the future of humanity that will represent a challenge from a social policy perspective.


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