I was going to edit my question to make some clarifications on the question. which in retrospect could, perhaps, have been more focused, in particular with respect to the notion of "collective intelligence". But then I realised that it would be better suited as an answer.
First let's look at how the cited paper discussed "collective intelligence":
Even though social psychologists have studied for decades how well groups perform specific tasks, they have not attempted to measure group intelligence in the same way individual intelligence is measured—by assessing how well a single group can perform a wide range of different tasks and using that information to predict how that same group will perform other tasks in the future. [...] By analogy with individual intelligence, we
define a group’s collective intelligence (c) as the
general ability of the group to perform a wide
variety of tasks. Empirically, collective intelligence
is the inference one draws when the ability of a
group to perform one task is correlated with that
group’s ability to perform a wide range of other
tasks. This kind of collective intelligence is a property
of the group itself, not just the individuals in it.
Here's the experiments:
In Study 1, 40 three-person groups worked together for up to 5 hours on a diverse set of simple group tasks plus a more complex criterion task. To guide our task sampling, we drew tasks from all quadrants of the McGrath Task Circumplex, a well-established taxonomy of group tasks based on the coordination processes they require. Tasks included solving visual puzzles, brainstorming, making collective moral judgments, and negotiating over limited resources. At the beginning of each session, we measured team members’ individual intelligence. And, as a criterion task at the end of each session, each group played checkers against a standardized computer opponent.
The quadrant refers to the following four items of collaboration:
- Generating ideas or plans
- Choosing a solution
- Negotiating a solution to a conflict
- Executing a task
The link between the tasks used in the first study and these quadrants is not specified in much detail, nor could I find details on how performance on the tasks was evaluated.
The paper also performed a second study with 152 groups ranging from two to five members. A subset of these groups (of unspecified size) worked on an additional five tasks, numbering ten in total.
Summarising the main results:
If c exists, what causes it? Combining the findings of the two studies, the average intelligence of individual group members was moderately correlated with c (r = 0.15, P = 0.04), and so was the intelligence of the highest-scoring team member (r = 0.19, P = 0.008). However, for both studies, c was still a much better predictor of group performance on the criterion tasks than the average or maximum individual intelligence.
We also examined a number of group and individual factors that might be good predictors of c. We found that many of the factors one might have expected to predict group performance—such as group cohesion, motivation, and satisfaction—did not.
However, three factors were significantly correlated with c. First, there was a significant correlation between c and the average social sensitivity of group members, as measured by the “Reading the Mind in the Eyes” test (15) (r = 0.26, P = 0.002). Second, c was negatively correlated with the variance in the number of speaking turns by group members, as measured by the sociometric badges worn by a subset of the groups (16) (r = –0.41, P = 0.01). In other words, groups where a few people dominated the conversation were less collectively intelligent than those with a more equal distribution of conversational turn-taking.
Finally, c was positively and significantly correlated with the proportion of females in the group (r = 0.23, P = 0.007). However, this result appears to be largely mediated by social sensitivity (Sobelz = 1.93, P = 0.03), because (consistent with previous research) women in our sample scored better on the social sensitivity measure than men [t(441) = 3.42, P = 0.001]. In a regression analysis with the groups for which all three variables (social sensitivity, speaking turn variance, and percent female) were available, all had similar predictive power for c, although only social sensitivity reached statistical significance (b = 0.33, P = 0.05).
So those are some highlights from the paper the claims are based on. I would say aspects of the paper are vague and some language is potentially misleading (particularly "collective intelligence"), but I find no reason to doubt the information given.
With respect to the claims made by some of the mainstream media based on this paper, I'll just focus on the claims made by one source in particular since other sources make similar types of claims. (I just chose the first source rather than selecting one based on content.)
Huffington Post: The Collective Intelligence of Women Could Save the World
Today’s greatest existential risks stem from advanced technologies like nuclear weapons, biotechnology, synthetic biology, nanotechnology, and even artificial superintelligence. These tools could trigger a disaster of unprecedented proportions. ... The good news is that none of these existential threats are inevitable. Humanity can overcome every single known danger. But accomplishing this will require the smartest groups working together for the common good of human survival. So, how do we ensure that we have the smartest groups working to solve the problem? Get women involved.
It is not clear how this conclusion can be drawn from the paper cited. There is only a speculative relation between the types of tasks defined for the "smartest groups" here (ability to face up to the mentioned "existential tasks") and the types of tasks used in the studies of the paper.
(But probably there are common-sense arguments for why the claim is true in that you want to draw from the broadest talent-pool possible, which should of course include women.)
Most of us are familiar with general human intelligence, which describes a person’s intelligence level across a broad spectrum of cognitive tasks. It turns out groups also have a similar “collective” intelligence that determines how successfully they can navigate these cognitive tasks.
This is misleading as (in particular) the phrase "these cognitive tasks" draws a false equivalence between the tasks used to measure individual intelligence and those used to measure "collective intelligence" in the paper. One (arguably two) on the original five collective tasks in the paper relate to traditional intelligence assessment techniques: visual puzzles (and arguably playing checkers). Other tasks—brainstorming, making moral judgments, and negotiation—have only a tenuous link with standard individual intelligence assessment.
This leads to the second unexpected discovery. Intuitively, one might think that groups with really smart members will themselves be really smart. This is not the case. The researchers found no strong correlation between the average intelligence of members and the collective intelligence of the group. Similarly, one might suspect that the group’s IQ will increase if a member of the group has a particularly high IQ. Surely a group with Noam Chomsky will perform better than one in which he’s replaced by Joe Schmo. But again, the study found no strong correlation between the smartest person in the group and the group’s collective smarts.
The study found a significant positive correlation between average individual intelligence (r = 0.15, P = 0.04) and "collective intelligence" and maximum individual intelligence (r = 0.19, P = 0.008) and "collective intelligence". Whether these count as "strong correlations", probably they do not. At the same time, the more problematic issue is the misleading representation of collective intelligence as indicating "smartness in groups". In some sense, the indirect language is getting more and more tenuous and further and further away from what the studies can actually tell us.
The last factor relates to the number of female members: the more women in the group, the higher the group’s IQ. As the authors of the study explained, “c was positively and significantly correlated with the proportion of females in the group.”
The phrase "group IQ" is problematic.
Everything else is fine, but it's worth noting that the correlation with respect to ratio of females was (r = 0.23, P = 0.007). Earlier, the correlation with respect to most intelligent member (r = 0.19, P = 0.008) was dismissed as "not a strong correlation". Granted the latter correlation is lower, but with a range of [−1,1], the difference between both correlations over the range of possible values is 2%. More importantly, it seems misleading to dismiss one correlation as not strong and herald the other as "positively and significantly correlated" even when that latter description applies equally to both.
If you find this surprising, you’re not alone: the authors themselves didn’t anticipate it, nor were they looking for a gender effect.
This is perhaps interesting in that the paper does not give details on the selection of members of groups, nor the relative gender balances and so forth. The gender issue was left rather as a postscript, but became the main talking point in the press.
Summary: The article on which the claims are based is quite vague on a lot of seemingly important details, such as how people were assigned to groups; the relative number of men and women from the general population sampled; how tasks such as "brainstorming", "making collective moral judgments", "negotiating over limited resources" were evaluated; the additional five tasks assigned in the second study, etc. Also the figure quoted in the OP tends to suggest that the trend is not clear-cut.
With respect to the media, the notion of collective intelligence proposed and evaluated in the paper has only a tenuous link with the context in which it is described in the cited articles. Many such articles put it forward as a sort of "group IQ" but the majority of tasks used in the study have only a tenuous relation with IQ. In general, the articles relegate the importance of individual intelligence in such groups while promoting the importance of having more women; even generously allowing "collective intelligence" as a proxy of "group IQ", both correlations were positive and significant and quite close—both variables had a similar effect.
Personal interpretation: In general, these articles promote the idea that groups with a higher ratio of women are naturally "smarter", that individual intelligence does not matter, and that this has been demonstrated scientifically. However, they sit on the politically correct interpretation of the principle they suggest to have scientific backing. For example, I do not find articles suggesting that groups consisting only of women are smarter than those with some men, despite this being a natural conclusion of the same principles they claim have scientific basis, nor do they suggest to fire men, irrespective of their individual intelligence, and hire women instead, based on the same principles.