Publications of Marno, H.

An object memory bias induced by communicative reference

In humans, a good proportion of knowledge, including knowledge about objects and object kinds, is acquired via social learning by direct communication from others. If communicative signals raise the expectation of social learning about objects, intrinsic (permanent) features that support object recognition are relevant to store into memory, while extrinsic (accidental) object properties can be ignored. We investigated this hypothesis by instructing participants to memorise shape-colour associations that constituted either an extrinsic object property (the colour of the box that contained the object, Experiment 1) or an intrinsic one (the colour of the object, Experiment 2). Compared to a non-communicative context, communicative presentation of the objects impaired participants’ performance when they recalled extrinsic object properties, while their incidental memory of the intrinsic shape-colour associations was not affected. Communicative signals had no effect on performance when the task required the memorisation of intrinsic object properties. The negative effect of communicative reference on the memory of extrinsic properties was also confirmed in Experiment 3, where this property was object location. Such a memory bias suggests that referent objects in communication tend to be seen as representatives of their kind rather than as individuals.

Toddlers favor communicatively presented information over statistical reliability in learning about artifacts

Observed associations between events can be validated by statistical information of reliability or by testament of communicative sources. We tested whether toddlers learn from their own observation of efficiency, assessed by statistical information on reliability of interventions, or from communicatively presented demonstration, when these two potential types of evidence of validity of interventions on a novel artifact are contrasted with each other. Eighteen-month-old infants observed two adults, one operating the artifact by a method that was more efficient (2/3 probability of success) than that of the other (1/3 probability of success). Compared to the Baseline condition, in which communicative signals were not employed, infants tended to choose the less reliable method to operate the artifact when this method was demonstrated in a communicative manner in the Experimental condition. This finding demonstrates that, in certain circumstances, communicative sanctioning of reliability may override statistical evidence for young learners. Such a bias can serve fast and efficient transmission of knowledge between generations.

Nonverbal communicative signals modulate attention to object properties.

We investigated whether the social context in which an object is experienced influences the encoding of its various properties. We hypothesized that when an object is observed in a communicative context, its intrinsic features (such as its shape) would be preferentially encoded at the expense of its extrinsic properties (such as its location). In the three experiments, participants were presented with brief movies, in which an actor either performed a non-communicative action towards one of five different meaningless objects, or communicatively pointed at one of them. A subsequent static image, in which either the location or the identity of an object changed, tested participants’ attention to these two kinds of information. Throughout the three experiments we found that communicative cues tended to facilitate identity change detection and to impede location change detection, while in the non-communicative contexts we did not find such a bidirectional effect of cueing. The results also revealed that the effect of the communicative context was due to the presence of ostensive-communicative signals before the object-directed action, and not to the pointing gesture per se. We propose that such an attentional bias forms an inherent part of human communication, and function to facilitate social learning by communication.