"Intersection Crossing" Project (2011 – Present)
Acronym: Intersection Crossing
Name: Competition between affordances while approaching an intersection
Type: Fundamental reseach
Funds: Doctoral fellowship (Contrat Doctoral, Ministère de l’Éducation Nationale de la Recherche et de Technologie)
key researchers: Antoine MORICE, Geoffrey MARTI, Gilles MONTAGNE
The project :
Driving a car is a typical situation in which an agent has to choose the most suitable maneuver to perform from multiple alternatives. Indeed, a safe approach to an intersection implies that drivers can simultaneously manage two scenarios: they either choose to cross or to give way to an oncoming vehicle. Gibson and Crooks (1938) proposed a theoretical framework capable of explaining driver's behavior in such a situation. In this seminal paper, they defined two major concepts: the Field of Safe Travel (FST) defined as the “field of possible paths which the car may take unimpeded” (p. 454), and the Minimum Stopping Zone (MSZ) defined as the “zone within which our driver could stop if he had to” (p. 457). Safe driving behavior was hypothesized to be the driver's response to the simultaneous perception of the boundaries of these two spatiotemporal regions, which would specify the driver's current crossing and stopping possibilities. Gibson and Crooks proposed that stopping-ability depends on the relation between FST and MSZ. They suggested that such an affordance can be formalized as the ratio between the FST and the MSZ.
Participant sat in a fixed-base simulator (Mobsim, France) in front of a large screen onto which a virtual scene was rear-projected by a video projector (Barco iQ R500) at a frame rate of 60 Hz. Their action of their right foot on the brake and accelerator pedals and their manipulation of the steering wheel (ECCI Trackstar 6000 GTS) were monitored via a USB signal sent to a computer that hosted a customized OpenGL virtual reality software that in turn updated the virtual scene.
From the participant's viewpoint, the visual scene was composed of an intersection formed by two straight, orthogonal roads, bordered by trees. An oncoming vehicle approached the intersection on this road.
Past Experiments :
Experiment #1 : First investigation of the role of CTcross and CTstop in decision making
Three groups of participants drove cars with identical acceleration capabilities but different braking capabilities and were asked to try to cross an intersection before an oncoming car traveling orthogonally blocked the route, if they deemed the maneuver to be safe. Alternatively, they could decide to stop before the intersection to let the oncoming car cross. Finally, as a last resort, they could decide to exit on the roadside. The intersections were identical among groups.
Results showed that although the crossing possibilities (CTcross) were the same for all groups, there were between-group differences in crossing frequency. This suggests that stopping possibilities (CTstop) play a role in the driver's decision-making process, in addition to the crossing possibilities. These results can be accounted for by a behavioral model of decision making, and provide support for the hypothesis of choice between affordances.
Key references (downloadable version in page Publications) :
- Marti, G., Morice, A.H.P. & Montagne, G. (2015) Drivers’ decision-making when attempting to cross an intersection results from competition betwwen affordances, Frontiers in Human Neurosciences, 8:1026. doi: 10.3389/fnhum.2014.01026