Human listeners provide insights into echo features used by dolphins (Tursiops truncatus) to discriminate among objects

Echolocating bottlenose dolphins (Tursiops truncatus) discriminate between objects on the basis of the echoes reflected by the objects. However, it is not clear which echo features are important for object discrimination. To gain insight into the salient features, the authors had a dolphin perform a match-to-sample task and then presented human listeners with echoes from the same objects used in the dolphin's task. In 2 experiments, human listeners performed as well or better than the dolphin at discriminating objects, and they reported the salient acoustic cues. The error patterns of the humans and the dolphin were compared to determine which acoustic features were likely to have been used by the dolphin. The results indicate that the dolphin did not appear to use overall echo amplitude, but that it attended to the pattern of changes in the echoes across different object orientations. Human listeners can quickly identify salient combinations of echo features that permit object discrimination, which can be used to generate hypotheses that can be tested using dolphins as subjects.     

Buzzwords: early cortical responses to emotional words during reading

Electroencephalographic event-related brain potentials were recorded as subjects read, without further instruction, consecutively presented sequences of words. We varied the speed at which the sequences were presented (3 Hz and 1 Hz) and the words' emotional significance. Early event-related cortical responses during reading differentiated pleasant and unpleasant words from neutral words. Emotional words were associated with enhanced brain responses arising in predominantly left occipito-temporal areas 200 to 300 ms after presentation. Emotional words were also spontaneously better remembered than neutral words. The early cortical amplification was stable across 10 repetitions, providing evidence for robust enhancement of early visual processing of stimuli with learned emotional significance and underscoring the salience of emotional connotations during reading. During early processing stages, emotion-related enhancement of cortical activity along the dominant processing pathway is due to arousal, rather than valence of the stimuli. This enhancement may be driven by cortico-amygdaloid connections.     

On undesirable consequences of thinking: framing effects as a function of substantive processing

Three studies investigate the impact of effortful constructive processing on framing effects. The results replicated previous findings: Participants avoided the risky option when the scenario was framed in terms of gains, but preferred this option when the scenario was framed in terms of losses. Importantly, framing effects were most pronounced when conditions allowed for an effortful constructive processing style (i.e., substantive processing). This impact of decision frames varied when decision time served as an indicator for the elaboration extent (Study 1), and also when processing motivation (accountability; Study 2) and processing ability (decision time; Study 3) were manipulated. Moreover, effortful processing did not increase framing effects when contextual cues reduced the necessity for constructive thinking (Study 1). We suggest that decision frames may take on very different roles as a function of the ambiguity of the decision problem, and the degree and style of processing. Copyright © 2006 John Wiley & Sons, Ltd.     

Fear of Hypoglycemia and Self Reported Posttraumatic Stress in Adults with Type I Diabetes Treated by Intensive Regimens

This study investigated the prevalence of hypoglycemic fear (FH) and hypoglycemia-specific posttraumatic stress (PTS) among individuals with Type I diabetes. Over 25% of participants met diagnostic criteria for current PTSD. High percentages of participants endorsed PTS symptom clusters, suggesting that individuals may be experiencing distress without necessarily meeting diagnostic criteria. Hierarchical multiple regression analyses revealed that perceived threat of death from hypoglycemia and FH were significantly related to PTS. Number of recent hypoglycemic episodes did not predict PTS/PTSD. Depression and nonspecific anxiety did not contribute to the statistical prediction of PTSD, suggesting that symptomatology endorsed represents hypoglycemia-specific anxiety rather than global psychological distress. The hypothesis that greater PTS symptomatology would relate to poorer glycemic control was unsubstantiated. Perceived death-threat from hypoglycemia and nonspecific anxiety were the only variables that contributed to prediction of glycemic control, suggesting that PTS did not represent a significant barrier for glycemic control in this sample.     

Characters named Charles or Charley in novels by Charles Dickens

12 fictional characters named Charles or Charley are contained in eight of the 14 completed novels by Charles Dickens. Most of the author's namesakes have humorous attributes, an unusually close relationship with one or more other characters, and a happy subsequent life. Three stages of the author's adult life are youthful, mature, and after separation from his wife. The fictional namesakes are most humorous in the author's youthful stage and least humorous after separation from his wife. The 12 fictional namesakes of Charles Dickens are compared with the two fictional namesakes of Jane Austen.     

The configuration and relaxation of motor task sets

Often the performance of a task does not only require the processing of certain stimuli in certain ways, but also certain patterns of interlimb coordination. We studied shifts between different tasks involving different patterns of intermanual coupling by means of the timed-response procedure, which allows to trace state variables related to task sets. The tasks required the production of rapid bimanual reversal movements with symmetric or parallel directions. Symmetric movements are associated with symmetric coupling, as indicated by positive intermanual correlations between the directions of left-hand and right-hand movements, whereas parallel movements are associated with parallel coupling, as indicated by negative intermanual correlations. Task switches were associated with gradual changes of the intermanual correlations, which indicate the state of intermanual coupling as a major ingredient of a task set, in the course of action preparation. At short preparation intervals intermanual correlations were those appropriate for the preceding trial; with increasing preparation time they were replaced by those appropriate for the current trial, but the influence of the preceding trial did not disappear completely. In-between trials, intermanual coupling drifted toward a symmetric coupling, but not to uncoupled limbs. After a change of the task the specification of movement directions was slowed, but its initiation was not delayed. According to these results, task sets relax toward attractors which can be different from the absence of task sets. They are gradually configured during task preparation with a persistent influence of the preceding task, and the specification of response characteristics does not wait until the configuration of the new task set is completed. The research reported in this paper was supported by grant He 1187/14-1 of the Deutsche Forschungsgemeinschaft. We thank Barbara Herbst, Holger Küper, Kevin Schepers, and Elisei Rotaro for their support in running the experiment.     

Postintentional neglect

F. Mechsner (2004) seems to deny a functional importance of postintentional processes, except that their characteristics can be taken into account at the perceptual-cognitive level of control. In that perspective, processes that are critical for the understanding of motor control and its limitations are neglected. On the other hand, the functional importance of task conceptions or task sets, which can vary and affect performance even for tasks that appear identical to an observer, is emphasized.     

Demands on attention and the role of response priming in visual discrimination of feature conjunctions

This study examined how response mapping of features within single- and multiple-feature targets affects decision-based processing and attentional capacity demands. Observers judged the presence or absence of 1 or 2 target features within an object either presented alone or with distractors. Judging the presence of 2 features relative to the less discriminable of these features alone was faster (conjunction benefits) when the task-relevant features differed in discriminability and were consistently mapped to responses. Conjunction benefits were attributed to asynchronous decision priming across attended, task-relevant dimensions. A failure to find conjunction benefits for disjunctive conjunctions was attributed to increased memory demands and variable feature-response mapping for 2- versus single-feature targets. Further, attentional demands were similar between single- and 2-feature targets when response mapping, memory demands, and discriminability of the task-relevant features were equated between targets. Implications of the findings for recent attention models are discussed.