Paul E. Meehl's contributions to personality assessment

Many of Meehl's interests converged in his work on personality assessment. In empirical research, development of the K scale of the Minnesota Multiphasic Personality Inventory and various scales of other tests are noteworthy, but his most profound contributions were conceptual and philosophical. Essays on the role of base rates in clinical decision and on construct validity in psychological tests provided vital insights on core issues in assessment. The concept of nomological nets allowed systematic investigation of unobservable theoretical entities, with liberating effects on all natural sciences. An active clinician, Meehl understood deeply the complexities of professional service, but his insistence on empirical validation as the ultimate arbiter of the value of any procedure required all attainable rigor in the scientific foundations of clinical practice.     

Measurement of speech disfluency through magnitude estimation and interval scaling

The purpose was to assess whether equal-appearing interval or magnitude-estimation scaling resulted in a data set with a closer correlation to the physical stimuli, made up of speech samples with varying amounts of disfluency. 20 young adults completed two tasks. In Task 1, subjects used a 7-point equal-appearing interval scale to rate the disfluency of 10 speech samples having varying within sentence pause, presented randomly at 65 dB SPL. In Task 2, subjects used magnitude-estimation scaling to rate these stimuli, presented in a randomized order. Analysis showed significantly high correlations for both scaling techniques and the speech stimuli (Spearman rho=.90 and 1.00, respectively). It appears that subjects can use either scaling technique to rate accurately varied speech disfluency.     

Reduced electrodermal activity in psychopathy-prone adolescents

This study tests the hypothesis that psychopathy-prone adolescents show reduced anticipatory skin conductance responding. Electrodermal activity was recorded while participants anticipated and responded to a 105 dB signaled or unsignaled white-noise burst. Using an extreme groups design, the authors used Child Psychopathy Scale (D. R. Lynam, 1997) scores from a community sample of 335 male adolescents (age 16) to form control (n = 65) and psychopathy-prone (n = 65) groups. Significantly more psychopathy-prone participants were nonresponders in the signaled anticipatory (p = .014), signaled responsivity (p = .037), and unsignaled responsivity (p = .003) conditions compared with controls. Anticipatory hyporesponsivity of psychopathy-prone adolescents similar to the electrodermal hyporesponsivity found in psychopathic adults suggests that this autonomic impairment is present by adolescence and may predispose individuals to adult psychopathy.     

Evaluation of Five Procedures for Classification of Participants’ Fear Levels

The present study evaluated the ability of 5 different fear classification procedures to discriminate between 3 fear levels and to correlate with 6 commonly used dependent measures of fear. A standardized fear assessment procedure was administered on 2 separate trials to 71 women participants. Following the completion of the assessment trials, the participants data were scored and regrouped according to 5 fear classification procedures (behavioral, self-report, skin conductance level, skin response amplitude, and heart rate). This design permitted each procedure to be evaluated to the same target stimulus and at the same point in time. The classifications of participants on the basis of behavior and skin conductance response were found to be most effective selection procedures with self-report, skin conductance level, and heart rate being the least. Reliability of the findings was assessed by a test–retest procedure.     

Hippocampal inactivation enhances taste learning

Learning tasks are typically thought to be either hippocampal-dependent (impaired by hippocampal lesions) or hippocampal-independent (indifferent to hippocampal lesions). Here, we show that conditioned taste aversion (CTA) learning fits into neither of these categories. Rats were trained to avoid two taste stimuli, one novel and one familiar. Muscimol infused through surgically implanted intracranial cannulae temporarily inactivated the dorsal hippocampus during familiarization, subsequent CTA training, or both. As shown previously, hippocampal inactivation during familiarization enhanced the effect of that familiarization on learning (i.e., hippocampal inactivation enhanced latent inhibition of CTA); more novel and surprising, however, was the finding that hippocampal inactivation during training sessions strongly enhanced CTA learning itself. These phenomena were not caused by specific aspects of our infusion technique--muscimol infusions into the hippocampus during familiarization sessions did not cause CTAs, muscimol infusions into gustatory cortex caused the expected attenuation of CTA, and hippocampal inactivation caused the expected attenuation of spatial learning. Thus, we suggest that hippocampal memory processes interfere with the specific learning mechanisms underlying CTA, and more generally that multiple memory systems do not operate independently.     

A simplified technique for scoring DSM-IV personality disorders with the Five-Factor Model

The current study compares the use of two alternative methodologies for using the Five-Factor Model (FFM) to assess personality disorders (PDs). Across two clinical samples, a technique using the simple sum of selected FFM facets is compared with a previously used prototype matching technique. The results demonstrate that the more easily calculated counts perform as well as the similarity scores that are generated by the prototype matching technique. Optimal diagnostic thresholds for the FFM PD counts are computed for identifying patients who meet diagnostic criteria for a specific PD. These threshold scores demonstrate good sensitivity in receiver operating characteristics analyses, suggesting their usefulness for screening purposes. Given the ease of this scoring procedure, the FFM count technique has obvious clinical utility.     

The roots of self-awareness

In this paper we provide an account of the structural underpinnings of self-awareness. We offer both an abstract, logical account – by way of suggestions for how to build a genuinely self-referring artificial agent – and a biological account, via a discussion of the role of somatoception in supporting and structuring self-awareness more generally. Central to the account is a discussion of the necessary motivational properties of self-representing mental tokens, in light of which we offer a novel definition of self-representation. We also discuss the role of such tokens in organizing self-specifying information, which leads to a naturalized restatement of the guarantee that introspective awareness is immune to error due to mis-identification of the subject.     

A spatial analysis of the discriminability of forms in noise

Multidimensional scaling (MDS) techniques were used to study the form characteristics which transcend noise in a discrimination task. Three dimensions of random polygons were identified and were psychophysically related to quantifted form measures.     

The influence of perceptual anchors and visual noise on the vertical-horizontal illusion

In an earlier study Chapanis and Mankin examined the vertical-horizontal illusion in a visually-rich environment. In that study they feit that perceptual anchors and visual noise may have influenced the Ss’ estimates of the real-world objects that were used as stimuli. The present experiment attempted to test in a controlled laboratory environment the questions raised in the previous experiment. In the present experiment Ss were asked to estimate the height of a vertical stimulus line by indicating its corresponding horizontal distance. The vertical stimulus line was presented in a background of visual noise and potential anchors. The results indicate that the anchors did influence estimates and that this influence was, in turn, affected by the visual noise.