HumansPosted by Audrey Dussutour Tue, May 17, 2011 10:16:26http://www.wired.com/wiredscience/2011/05/wisdom-of-crowds-decline/
How social influence can undermine the wisdom of crowd effect
Social groups can be remarkably smart and knowledgeable when their averaged judgements are compared with the judgements of individuals. Already Galton found evidence that the median estimate of a group can be more accurate than estimates of experts. This wisdom of crowd effect was recently supported by examples from stock markets, political elections, and quiz shows [Surowiecki J (2004) The Wisdom of
Crowds]. In contrast, we demonstrate by experimental evidence (N = 144) that even mild social influence can undermine the wisdom of crowd effect in simple estimation tasks. In the experiment, subjects could reconsider their response to factual questions after having received average or full information of the responses of other subjects. We compare subjects’ convergence of estimates and improvements in accuracy over five consecutive estimation periods with a control condition, in which no information about others’ responses was provided. Although groups are initially “wise,” knowledge about estimates of others narrows the diversity of opinions to such an extent that it undermines the wisdom of crowd effect in three different ways. The “social influence effect” diminishes the diversity of the crowd without improvements of its collective error. The “range reduction effect” moves the position of the truth to peripheral regions of the range of estimates so that the crowd becomes less reliable in providing expertise for external observers. The “confidence effect” boosts individuals’ confidence after convergence of their estimates despite lack of improved accuracy. Examples of the revealed mechanism range from misled elites to the recent global financial crisis.
ModellingPosted by Audrey Dussutour Tue, May 03, 2011 19:43:00
A nice review by Jens Krause, Alan Winfield and Jean-Louis Deneubourg
Interactive robots have the potential to revolutionise the study of social behaviour because they provide several methodological advances. In interactions with live ani
mals, the behaviour of robots can be standardised, morphology and behaviour can be decoupled (so that different morphologies and behavioural strategies can be combined),behaviour can be manipulated in complex interaction sequences and models of behaviour can be embodied by the robot and thereby be tested. Furthermore, robots can be used as demonstrators in experiments on social learning. As we discuss here, the opportunities that robots create for new experimental approaches have farreaching consequences for research in fields such as mate choice, cooperation, social learning, personality studies and collective behaviour.
AnimalsPosted by Audrey Dussutour Wed, April 27, 2011 10:25:45Fire ants self-assemble into waterproof rafts to survive floods
Why does a single fire ant Solenopsis invicta struggle in water,
whereas a group can float effortlessly for days? We use time-lapse
photography to investigate how fire ants S. invicta link their bodies
together to build waterproof rafts. Although water repellency in
nature has been previously viewed as a static material property
of plant leaves and insect cuticles, we here demonstrate a selfassembled
hydrophobic surface.We find that ants can considerably
enhance their water repellency by linking their bodies together,
a process analogous to the weaving of a waterproof fabric. We
present a model for the rate of raft construction based on observations
of ant trajectories atop the raft. Central to the construction
process is the trapping of ants at the raft edge by their neighbors,
suggesting that some “cooperative” behaviors may rely upon
HumansPosted by Audrey Dussutour Wed, April 27, 2011 10:11:49How simple rules determine pedestrian behavior and crowd disastersABSTRACT
With the increasing size and frequency of mass events, the study of
crowd disasters and the simulation of pedestrian flows have
become important research areas. However, even successful modeling
approaches such as those inspired by Newtonian force models
are still not fully consistent with empirical observations and are
sometimes hard to calibrate. Here, a cognitive science approach is
proposed, which is based on behavioral heuristics.Wesuggest that,
guided by visual information, namely the distance of obstructions
in candidate lines of sight, pedestrians apply two simple cognitive
procedures to adapt their walking speeds and directions. Although
simpler than previous approaches, this model predicts individual
trajectories and collective patterns of motion in good quantitative
agreement with a large variety of empirical and experimental data.
This model predicts the emergence of self-organization phenomena,
such as the spontaneous formation of unidirectional lanes or
stop-and-go waves. Moreover, the combination of pedestrian heuristics
with body collisions generates crowd turbulence at extreme
densities—a phenomenon that has been observed during recent
crowd disasters. By proposing an integrated treatment of simultaneous
interactions between multiple individuals, our approach
overcomes limitations of current physics-inspired pair interaction
models. Understanding crowd dynamics through cognitive heuristics
is therefore not only crucial for a better preparation of safe
mass events. It also clears the way for a more realistic modeling
of collective social behaviors, in particular of human crowds and
biological swarms. Furthermore, our behavioral heuristics may
serve to improve the navigation of autonomous robots.
Micro-organismsPosted by Audrey Dussutour Mon, January 24, 2011 11:30:20
In the study, "Primitive agriculture in a social amoeba", in the current Nature
journal, a team led by evolutionary ecologist Debra Brock
of Rice University in Houston reports that, "the social amoeba Dictyostelium discoideum
has a primitive farming symbiosis that includes dispersal and prudent harvesting of the crop."
AnimalsPosted by David Sumpter Wed, November 17, 2010 20:34:11
Last week I was at the collective motion meeting at the Max Plank Institute in Dresden (COLMOT10
). The meeting involved physicists and biologists interesting in understand the motion of animal groups: mainly bird flocks, fish schools and so on. The main message of the meeting was that all flocks are the same but at the same time different. They are same in the sense that there are a limited number of collective patterns (such as aligned motion, phase transitions, torus etc.) which can arise from models. They are different in that the rules of interaction for different species are very different. It was encouraging to see more new data presented at this meeting than at earlier such meetings (on the animal side this was mainly by Irene Giardina
, Iain Couzin
and Jacques Gautrais
). But I think we still need to be more focused on data.
Apparently this was one of Max Plank Institute's most oversubscribed meeting and as a reward they have suggested a next meeting in Majorca!
GeneralPosted by David Sumpter Sun, November 07, 2010 10:40:10
Last week I was at a final grant reporting meeting for the Human Frontiers grant
I had together with Madeleine Beekman, Martin Middendorf and Toshi Nakagaki. Having this grant was lots of fun both from a scientific point of view and because its so much fun to work with other people from all rund the world.
Apart from us, the meeting had very few fellows and grants involving modelling or collective behaviour, although the HFSP people kept saying how important these things are. So I would encourage anyone involved in collective behaviour research to apply either for a fellowship or a team grant.
AnnouncementsPosted by David Sumpter Sun, October 24, 2010 20:53:52
Finally, after what I think seemed like quite a long wait my book "Collective Animal Behavior
" is available on Amazon. Please buy it. I might try to update the blog a little more often now too!