Cognitive capacities for behavioural flexibility in wild chimpanzees (Pan troglodytes): the effect of snare injury on complex manual food processing

In chimpanzees, it is only in the restricted context of tool use that manual and cognitive skills have been described, comparable to those that gorillas and orang-utans display in obtaining plant foods. We report the complex food preparation skills used to eat, without tools, the leaves of the tree Broussonettia papyrifera in the Sonso community of chimpanzees at Budongo Forest, Uganda. Able-bodied individuals used multi-stage techniques that required bimanual role differentiation at several stages, and were hierarchical in organisation. A total repertoire of 14 techniques was found, with strong preference in all individuals for either of two of these; 6 additional techniques were found when flowers and leaves were eaten together. However, in this community over 20% of individuals suffer from some form of upper- or lower-limb injury as a result of snares. We investigated the manner of compensation for upper-limb injury. Only the most severely injured showed reduced feeding efficiency. Injured individuals were found to use the same repertoire of techniques as able-bodied chimpanzees. We found no evidence to suggest that injured individuals were able to develop wholly novel techniques optimal for their specific injuries, although shifts in preference for particular techniques did occur. Rather, injured individuals used novel ways of achieving particular steps in the process; by "working around" their impairments; in this way, they managed to use the same techniques as the able-bodied. Since snare injuries generally befall young animals, these results suggest that chimpanzees learn techniques partly through observational learning (of, necessarily, able-bodied individuals). Accepted after revision: 8 February 2001 Electronic Publication     

The liebowitz social anxiety scale as a self-report instrument: a preliminary psychometric analysis

The Liebowitz social anxiety scale (LSAS) is a commonly used clinician-administered instrument. The present study reports on the properties of a self-report version of the LSAS (LSAS-SR). About 175 participants diagnosed with social phobia participated in the study. The LSAS-SR showed overall good psychometric properties as indicated by the results of test-retest reliability, internal consistency, and convergent and discriminant validity. Furthermore, the scale was sensitive to treatment change. The construct validity of the LSAS-SR, however, remains to be further explored. These findings support the utility of the LSAS-SR, which has the advantage of saving valuable clinician time compared to the clinician-administered version.     

Memory for frequency of bizarre and common stimuli: limitations of the automaticity hypothesis

In 2 experiments, the influence of intention to process frequency on accuracy of memory for frequency of bizarre and common sentences was investigated. The results from multiple regression analyses indicated that intentional processing increased the accuracy of frequency judgments when memory for frequency was tested after a 2-min (Experiment 1) and after a 48-hr (Experiment 2) retention interval. Furthermore, the results of Experiment 2 indicated that unintentional processors tended to overestimate frequencies of bizarre relative to common items after a delay. The implications of the results are discussed with regard to L. Hasher and R. T. Zacks's (1984) automaticity hypothesis, human performance, and the accuracy of judgments of frequency of occurrence of unusual events.     

Effects of stress and hippocampal NMDA receptor antagonism on recognition memory in rats

Exposures to uncontrollable stress have been shown to alter ensuing synaptic plasticity in the hippocampus and interfere with hippocampal-dependent spatial memory in rats. The present study examined whether stress, which impairs hippocampal long-term potentiation (LTP), also affects (nonspatial) hippocampal-dependent object-recognition memory, as tested on the visual paired comparison task (VPC) in rats. After undergoing an inescapable restraint–tailshock stress experience, rats exhibited markedly impaired recognition memory at the 3-h (long) familiarization-to-test phase delay but not at the 5-min (short) delay. In contrast, unstressed control animals showed robust recognition memory (i.e., they exhibited reliable preferences for novel over familiar objects) at both short- and long-delay periods. The impairing effect of stress on long-delay recognition memory was transient because 48 h after undergoing stress experience, animals performed normally at the long delay. Similar to stress, microinfusions of DL-2-amino-5-phosphonovaleric acid (APV), a competitive N-methyl-D-aspartate receptor (NMDAR) antagonist that blocks LTP, into the dorsal hippocampus selectively impaired object-recognition memory at the long-delay period. Together, these results suggest that stress and intrahippocampal administration of APV affect recognition memory by influencing synaptic plasticity in the hippocampus.

[The following individuals kindly provided reagents, samples, or unpublished information as indicated in the paper H. Blair.]

     

A systematic investigation of same and cross modality priming using written and spoken responses

Effects of presentation modality and response format were investigated using visual and auditory versions of the word stem completion task. Study presentation conditions (visual, auditory, non-studied) were manipulated within participants, while test conditions (visual/written, visual/spoken, auditory/written, auditory/spoken, recall-only) were manipulated between participants. Results showed evidence for same modality and cross modality priming on all four word stem completion tasks. Words from the visual study list led to comparable levels of priming across all test conditions. In contrast, words from the auditory study list led to relatively low levels of priming in the visual/written test condition and high levels of priming in the auditory/spoken test condition. Response format was found to influence priming performance following auditory study in particular. The findings confirm and extend previous research and suggest that, for implicit memory studies that require auditory presentation, it may be especially beneficial to use spoken rather than written responses.     

Actual versus self-reported scholastic achievement of litigating postconcussion and severe closed head injury claimants

Psychologists typically rely on patients' self-report of premorbid status in litigated settings. The authors examined the fidelity between self-reported and actual scholastic performance in litigating head injury claimants. The data indicated late postconcussion syndrome (LPCS) and severe closed head injury litigants retrospectively inflated scholastic performance to a greater degree than nonlitigating control groups. The LPCS group showed the highest magnitude of grade inflation, but discrepancy scores did not significantly correlate with a battery of malingering measures or with objective cerebral dysfunction. These findings support previous studies, which showed self-report is not a reliable basis for estimation of preinjury cognitive status. Retrospective inflation may represent a response shift bias shaped by an adversarial context rather than a form of malingering.     

Cancer Problems in Living and Quality of Life After Bone Marrow Transplantation

This study was conducted to develop an objective problems-in-living scale to identify the needs of cancer survivors after a demanding treatment such as bone marrow transplantation (BMT). A total of 99 adult BMT survivors completed questionnaires containing the 29 items included in the Cancer Problems-In-Living Scale (CPILS). These BMT survivors were most concerned about return of their illness or relapsing, the future, fatigue, not physically being able to have sexual intercourse, changes in their physical appearance, being concerned about infection and crowds, difficulty in obtaining adequate insurance, losing health insurance by changing jobs, and difficulty in meeting medical expenses. The CPILS showed a good level of internal consistency ( = .91). The hypothesis that BMT survivors who had lower levels of physical functioning would experience more problems with living was supported by correlation (.48, p < .001) of the CPILS with the Self-Rated Karnofsky Performance Scale. The construct validity of the CPILS was further supported by a significant negative correlation (–.66, p < .002) with the scores of BMT survivors on a quality-of-life measure, the Satisfaction with Life Domains Scale for BMT.     

Neural representation for the perception of the intentionality of actions

A novel population of cells is described, located in the anterior part of the superior temporal sulcus (STSa, sometimes called STPa) of the temporal lobe in the macaque monkey. These cells respond selectively to the sight of reaching but only when the agent performing the action is seen to be attending to the target position of the reaching. We describe how such conditional selectivity can be generated from the properties of distinct cell populations within STSa. One cell population responds selectively to faces, eye gaze, and body posture, and we argue that subsets of these cells code for the direction of attention of others. A second cell population is selectively responsive to limb movement in certain directions (e.g., responding to an arm movement to the left but not to an equivalent leg movement or vice versa). The responses of a subset of cells sensitive to limb movement are modulated by the direction of attention (indicated by head and body posture of the agent performing the action). We conclude that this combined analysis of direction of attention and body movements supports the detection of intentional actions.     

Feeling safe at work: Development and validation of the Psychological Safety Inventory

Psychological safety, defined as perceptions that an individual within a team is supported and feels safe to take interpersonal risks, voice opinions, and share ideas, is vital for organizational effectiveness. However, there is no consensus on how workplace psychological safety should be measured. We developed the Psychological Safety Inventory (PSI) in response to organizational needs to accurately assess psychological safety. A 70-item version of the PSI was administered to 497 employees from Canada, the United States, and the United Kingdom. Based on factor analytic findings, we reduced the preliminary PSI to a 30-item, five-factor scale. The PSI showed high reliability and correlated as anticipated with convergent measures. Overall, the PSI is a valid and reliable measure of workplace psychological safety.