Potentiation and overshadowing in preweanling and adult rats

Four experiments compared the aversion acquired by 18-day-old and 60-day-old rats to a flavor that was either tasted alone or in combination, simultaneously or successively, with another flavor when paired with illness. The purpose was to study temporal variables and theoretical issues pertinent to potentiation and overshadowing while investigating ontogenetic differences in these phenomena. When either the preweanlings or the adults were presented a simultaneous compound flavor (sucrose/coffee) followed by lithium chloride-induced illness, greater sucrose aversions were found than for animals conditioned on sucrose alone--that is, potentiation. Preweanlings demonstrated greater potentiation than did adults, whether the conditioned stimulus-unconditioned stimulus (CS-US) delay was 0 or 1 hr. This potentiation was eliminated by nonreinforced presentations of the alternative CS element. Potentiation was not seen when the two flavors were presented successively as the CS; instead, overshadowing occurred. Tests of configuring by extinction procedures indicated a tendency for these animals to form a configured representation of the simultaneous compound solution. This disposition for configuring tended to be more pronounced for preweanlings than for adults. Ontogenetic differences in response to configuration, CS saliency, and generalization decrement seem consistent with at least one model of potentiation and the ontogenetic differences in potentiation seen in the present experiments.     

Detection of malingering of psychiatric disorder with the personality assessment inventory: an investigation of criminal defendants

To assess the diagnostic accuracy of the Personality Assessment Inventory (PAI; Morey, 1991) Validity scales for the detection of malingered psychiatric disorders, we divided a sample of criminal defendants referred for forensic evaluation by the federal courts into malingering and not malingering groups based on their performance on the Structured Interview of Reported Symptoms (Rogers, Gillis, & Bagby, 1990). Logistic regression analyses (LGAs) revealed that there were no differences between the malingering and not malingering groups with respect to age, race, years of education, history of drug abuse, or number of previous felony convictions. LGA with malingering versus not malingering as the criterion revealed that the PAI Negative Impression Management (NIM) scale but not the Rogers Discriminant Function (RDF; Rogers, Sewell, Morey & Ustad, 1996) nor the Malingering index (MAL; Morey, 1996) significantly differentiated the malingering from the not malingering group. Receiver operating characteristics analyses demonstrated acceptable sensitivity and specificity for the NIM scale but not the RDF scale or the MAL index. We discuss the results in terms of the suggested cutoff scores for the PAI Validity scales in detecting criminal defendants who are attempting to feign psychiatric disorder.     

The utility of the MMPI-2 malingering discriminant function index in the detection of malingering: a study of criminal defendants

This study examined the utility of the Minnesota Multiphasic Personality Inventory-2's (MMPI-2) malingering discriminant function index (M-DFI), recently developed by Bacchiochi and Bagby, in the detection of malingering in a forensic sample. Criminal defendants were divided into "malingering" and "not malingering" groups using the structured interview of reported symptoms (SIRS) criteria proposed by Rogers. Logistic regression analysis (LRA) revealed that the MMPI-2 infrequency (F) scale had the best predictive utility of the traditional infrequency scales. Although the M-DFI did significantly differentiate the malingering from the not malingering groups, it did not add significantly to the predictive utility of the MMPI-2 F scale. Receiver operating characteristics analyses demonstrated acceptable sensitivity and specificity for the MMPI-2 F scale, but poor sensitivity for the M-DFI scale. The results are discussed in terms of the utility of the M-DFI in detecting malingering and problems of extending the findings of simulation studies to the forensic context.     

Detection of Malingering of Psychiatric Disorder With the Personality Assessment Inventory: An Investigation of Criminal Defendants

582 Ss in 8 experiments viewed 1 of 9 films portraying models involved in achievement (Ach), affiliation (Aff), or neutral (Neu) activity. Ss who viewed Ach models after an interval of adaptation to the setting produced more TAT n Ach immediately after the film than other adapted Ss. Under other conditions, Ss who viewed Ach models produced significantly less n Ach than Ss who viewed non-Ach models. Results were ordered to a “subself” conception of personality organization and three theoretical propositions: (a) Models elicit fantasy thematically similar to their activity unless S is incompatibly preoccupied, (b) in which case models cause suppression of similar fantasy; but (c) in fantasy both elicitation and suppression are short-lived.     

Psychopathy and malingering of psychiatric disorder in criminal defendants

Because the use of deception is an important clinical characteristic of psychopathy, there is intuitive appeal to the idea that psychopathy and malingering are associated. There is, however, very little research showing that psychopaths are more likely to malinger. We classified a sample of criminal defendants as high, moderate, or low in psychopathy, based on PCL-R scores, and compared their scores on indices typically used to detect malingering on the MMPI-2, the PAI and the SIRS. The high psychopathy group scored significantly higher on the MMPI-2 F and F-K; the PAI NIM, and the SIRS, but not the MMPI-2 Fb, F(p), or the PAI RDF or Mal, lending some support for the DSM-IV recommendation that malingering should be considered whenever there is a diagnosis of antisocial personality disorder. Logistic regression analysis (LGA) revealed that Factor I but not Factor II of the PCL-R significantly discriminated malingerers from nonmalingerers with 75% correct classification. However, receiver operating characteristic (ROC) analysis revealed that psychopathy ratings had poor sensitivity and specificity in the detection of malingering. Calculation of the percentages of those exceeding accepted cut-offs on each of the malingering measures revealed that a high percentage of severe psychopaths did not attempt to feign psychiatric disorder. The results suggest that psychopathy is not a clinically useful indictor of malingering. The results are discussed in terms of confirmatory bias and the impact such a bias could have on the evaluation of criminal defendants.     

Unilateral olfactory conditioning in 6-day-old rat pups

The potential that early olfactory learning might be laterally organized in the brain was investigated in 6-day-old rats. This hypothesis is based on the finding that the commissural systems that subserve bilateral olfactory communication do not mature until the second week of postnatal life. Pups were trained with pairings of cedar odor and intraoral infusions of milk while one nostril was occluded. Animals expressed a conditioned orientation towards cedar if tested with the trained nostril open. No such conditioning was observed if the untrained nostril was open during testing. Further, when individual pups received cedar odor/milk pairings with one nostril open and orange odor/milk pairings with the other open, they expressed a conditioned preference for orange when tested with the orange-trained nostril open, and a preference for cedar when tested with the cedar-trained nostril open. Classically conditioned oral responses (mouthing) also appeared to be lateralized. However, no such unilateral conditioning occurred with respect to behavioral activation, which is also conditioned in this paradigm. Increases in activity to the odor CS were observed regardless of whether the trained or untrained nostril was open during testing. These results suggest that in developing rodents, olfactory memories may be partly represented in structures that can be unilaterally accessed during training and testing. They provide a starting point for isolation of neural substrates of the olfactory conditioning process.     

Potentiation of a conditioned taste aversion in preweanling and adult rats

Preweanling (18 days old) and adult rats were made ill with LiCl either 2 min or 1 hr after tasting controlled amounts of either one of two single flavors (saccharin or NaCl) or a compound mixture of the two. Conditioning was assessed with a single test 4 days later relative to explicitly unpaired control conditions. Generally, potentiation of the aversions to either flavor occurred for animals conditioned to the compound. The potentiation effect was decreased or eliminated by nonreinforced exposure to the alternative flavor of the compound. These effects tended to be stronger for the younger rats. Specifically, adult animals did not express potentiation of the saccharin aversion whereas preweanlings expressed potentiated salt aversions. Nonreinforced exposure to the alternative element eliminated the potentiation effect. Conditions conducive to potentiation are discussed in light of investigators who have not observed this effect in similar studies with compound stimuli.     

Factors affecting career retention among naval aviators

Typically, retention studies have emphasized those who separate rather than those who choose a naval career. The present study examined factors that contribute to career satisfaction and aviators' decisions to remain in naval aviation. Primary reasons for remaining in naval aviation were the enjoyment of flying, coupled with the self-esteem associated with being a naval aviator. Career satisfaction for aviators was derived primarily from intrinsic motivators associated with flying and peer recognition.Opinions or conclusions contained in this report are those of the authors and do not necessarily reflect the views or the endorsement of the Navy Department. The research reported in this paper was completed under Naval Medical Research and Development Command work unit 63706N M0096 M00960.01.