Walter Hussy | Search PubMed

PubMed2005

How eyewitnesses resist misinformation: social postwarnings and the monitoring of memory characteristics.

Previous findings have been equivocal as to whether the postevent misinformation effect on eyewitness memory is reduced by warnings presented after the misinformation (postwarnings). In the present research, social postwarnings, which characterize the postevent source as a low-credibility individual, diminished the misinformation effect in both cued recall and recognition tests. Discrediting the source as being either untrustworthy or incompetent was effective (Experiment 1). Also, postwarned participants rated reality characteristics of their memories more accurately than did participants receiving no or high-credibility information about the postevent source (Experiment 2). A social postwarning yielded the same results as an explicit source-monitoring appeal and led to longer response times for postevent items, relative to a no-warning condition (Experiments 3 and 4). The findings suggest that the reduced misinformation effect was due to more thorough monitoring of memory characteristics by postwarned participants, rather than to a stricter response criterion or to enhanced event memory.

Adult↗

PubMed2003

Human cortical object recognition from a visual motion flowfield.

Moving dots can evoke a percept of the spatial structure of a three-dimensional object in the absence of other visual cues. This phenomenon, called structure from motion (SFM), suggests that the motion flowfield represented in the dorsal stream can form the basis of object recognition performed in the ventral stream. SFM processing is likely to contribute to object perception whenever there is relative motion between the observer and the object viewed. Here we investigate the motion flowfield component of object recognition with functional magnetic resonance imaging. Our SFM stimuli encoded face surfaces and random three-dimensional control shapes with matched curvature properties. We used two different types of an SFM stimulus with the dots either fixed to the surface of the object or moving on it. Despite the radically different encoding of surface structure in the two types of SFM, both elicited strong surface percepts and involved the same network of cortical regions. From early visual areas, this network extends dorsally into the human motion complex and parietal regions and ventrally into object-related cortex. The SFM stimuli elicited a face-selective response in the fusiform face area. The human motion complex appears to have a central role in SFM object recognition, not merely representing the motion flowfield but also the surface structure of the motion-defined object. The motion complex and a region in the intraparietal sulcus reflected the motion state of the SFM-implicit object, responding more strongly when the implicit object was in motion than when it was stationary.

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