The parahippocampal cortex (PHC) has been implicated in the processing of place-related information. It has also been implicated in episodic memory, even for items that are not related to unique places. How could the same cortical region mediate such seemingly different cognitive processes? Both processes rely on contextual associations, and we therefore propose that the PHC should be viewed not as exclusively dedicated for analyzing place-related information, or as solely processing episodic memories, but instead as more generally playing a central role in contextual associative processing. To test this proposal, we created a novel learning paradigm to form new associations among meaningless visual patterns. These new associations were created to emulate either spatial or nonspatial contexts. Both spatial and nonspatial associations activated the PHC more than noncontextual items. Moreover, items from spatial contexts activated the posterior part of the PHC, whereas items from nonspatial contexts activated the anterior PHC. Therefore, we show that the PHC plays a role of processing contextual associations in general, and that these associations are not restricted to spatial information. By modifying the existing view of the PHC function accordingly, the seemingly contradicting processes that activate it can be reconciled under one overarching framework.

Studies of attentional capture by personally significant stimuli have reached inconsistent results, possibly because of improper control of the participants' attention. In the present study, the authors controlled visual attention by using a Stroop-like task. Participants responded to a central color and ignored a word presented either centrally (i.e., at the focus of attention) or peripherally (i.e., outside the focus of attention). Central words led to slower reaction times and larger orienting responses for significant items than for neutral items. These effects largely disappeared when the words appeared in a peripheral location. The peripheral words interfered with performance when they were relevant to task demands. These results indicate that there is a fundamental difference between task-relevant words and personally significant words: The former capture attention even when presented peripherally, whereas the latter do not.

No abstract

No abstract

Visual context plays a prominent role in everyday perception. Contextual information can facilitate recognition of objects within scenes by providing predictions about objects that are most likely to appear in a specific setting, along with the locations that are most likely to contain objects in the scene. Is such identity-related ("semantic") and location-related ("spatial") contextual knowledge represented separately or jointly as a bound representation? We conducted a functional magnetic resonance imaging (fMRI) priming experiment whereby semantic and spatial contextual relations between prime and target object pictures were independently manipulated. This method allowed us to determine whether the two contextual factors affect object recognition with or without interacting, supporting a unified versus independent representations, respectively. Results revealed a Semantic x Spatial interaction in reaction times for target object recognition. Namely, significant semantic priming was obtained when targets were positioned in expected (congruent), but not in unexpected (incongruent), locations. fMRI results showed corresponding interactive effects in brain regions associated with semantic processing (inferior prefrontal cortex), visual contextual processing (parahippocampal cortex), and object-related processing (lateral occipital complex). In addition, activation in fronto-parietal areas suggests that attention and memory-related processes might also contribute to the contextual effects observed. These findings indicate that object recognition benefits from associative representations that integrate information about objects' identities and their locations, and directly modulate activation in object-processing cortical regions. Such context frames are useful in maintaining a coherent and meaningful representation of the visual world, and in providing a platform from which predictions can be generated to facilitate perception and action.

The authors examined the incremental validity of the reaction time (RT) measure beyond that of skin conductance response (SCR) in the detection of concealed information. Participants performed a Stroop-like task in which they named the color of critical and neutral words. Results show that the SCR highly differentiated between the relevant and neutral words. However, the RT demonstrated a significant differentiation only when the critical words denoted personally significant items (e.g., one's own name) and not when they denoted crime-relevant items related to a simulated crime. In both cases, combining the 2 measures yielded no advantage over the use of SCR alone. Thus, although behavioral measures may differentiate between relevant and neutral information in some cases, their practical use is questionable.Scientists and forensic experts have attempted for many years to develop methods for the purpose of detecting concealed information. Several polygraph techniques assessing physiological responses have been proposed since the beginning of the 20th century for the detection of concealed information (for reviews, see

This study focused on the Guilty Knowledge Test (GKT) -a psychophysiological detection method based on a series of multiple-choice questions, each having one relevant and several neutral (control) alternatives. The study examined a new method, designed to reduce false-positive outcomes, due to leakage of relevant items to innocent suspects, by introducing target items (i.e. items known to all examinees, but unrelated to the crime), to which subjects have to respond (e.g., by pressing a key), while answering the GKT questions. Informed innocents showed relatively larger electrodermal responses to the critical items than uninformed participants, but not as large as the responses made by guilty participants. No differences between informed and uninformed innocents were obtained with a respiration measure. The use of the target items tended to reduce the differences between informed and uninformed innocents. The results further demonstrated that electrodermal responding to the relevant items was correlated with memory of these items.The Guilty Knowledge Test (GKT) is a method of psychophysiological detection that has been extensively researched and discussed in the literature (e.g., Ben-Shakhar, 1991;Furedy & Heslegrave, 1991;Lykken, 1974Lykken, , 1981. It utilizes a series of multiple-choice questions, each having one relevant alternative (e.g., a feature of the crime under investigation) and several neutral (control) alternatives, chosen so that an innocent suspect would not be able to discriminate them from the relevant alternative (Lykken, 1981). Typically, if the subject's physiological responses to the relevant alternative are consistently larger than the responses to all other alternatives, knowledge about the event (e.g., crime) is inferred.This method protects innocent suspects because, as long as information about the event has not been leaked out, the relevant and control questions should be equivalent from their perspective. Under these conditions, the probability that an innocent suspect would show consistently larger responsivity to the relevant alternative than to the neutral ones depends only on the number of questions and on the number of alternative answers per question, and this probability can be controlled such that maximal protection for the innocent is provided. Indeed, a relatively large number of studies, which were conducted to assess the accuracy of the GKT, reveal that the rate of false-positive errors (innocent suspects classified as guilty) is around 5% (for a review of these studies, see, Ben-Shakhar & Furedy, 1990;Elaad, 1998).However, a successful implementation of the GKT depends on the validity of the assumptions underlying it, and in particular on the assumption that the relevant information is not known to innocent suspects. This seems crucial because it has been

No abstract