Similarities and differences between MMPI and MMPI-2 applications to the assessment of posttraumatic stress disorder

The purpose of this study was to address the question: Is the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) comparable to the original MMPI in its applicability to the assessment of posttraumatic stress disorder (PTSD) among Vietnam combat veterans? The question was addressed by administering both the original MMPI and MMPI-2 to 29 subjects classified as meeting Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.; DSM-III-R) criteria for PTSD and comparing MMPI and MMPI-2 scores in terms of: degree of association, code-type congruence, diagnostic hit rates (when compared to two other clinical samples, and one normal sample), and congruence of the Keane PTSD Scale (PK). Results reveal highly significant correlations between MMPI and MMPI-2 basic scales for the PTSD sample as well as congruence in 2-point codes comparable to previous studies. The MMPI-2 was found to identify effectively PTSD subjects from the other groups. Results also showed a high degree of association between the MMPI and MMPI-2 in regard to PK scores, although minor differences were found in PK raw scores between the two tests. Overall, the findings suggest a high degree of comparability between the MMPI and MMPI-2 in the assessment of PTSD.     

The interplay between stereopsis and structure from motion

In a series of psychophysical experiments, an adaptation paradigm was employed to study the influence of stereopsis on perception of rotation in an ambiguous kinetic depth (KD) display. Without prior adaptation or stereopsis, a rotating globe undergoes spontaneous reversals in perceived direction of rotation, with successive durations of perceived rotation being random variables. Following 90 sec of viewing a stereoscopic globe undergoing unambiguous rotation, the KD globe appeared to rotate in a direction opposite that experienced during the stereoscopic adaptation period. This adaptation aftereffect was short-lived, and it occurred only when the adaptation and test figures stimulated the same retinal areas, and only when the adaptation and test figures rotated about the same axis. The aftereffect was just as strong when the test and adaptation figures had different shapes, as long as the adaptation figure contained multiple directions of motion imaged at different retinal disparities. Nonstereoscopic adaptation figures had no effect on the perceived direction of rotation of the ambiguous KD figure. These results imply that stereopsis and motion strongly interact in the specification of structure from motion, a result that complements earlier work on this problem.     

Developmental change in visual information processing under backward masking

Four-year-olds, eight-year-olds, and college students were compared with respect to their speed and strategy for processing form information in a pointing-recognition task. The target form arrays, varying in size from one to four forms, were presented tachistoscopically, followed by a masking array at varying intervals. No age differences in processing speed were found on single-item arrays, but four-year-olds were progressively slower as array size increased. A selective processing condition resulted in longer processing times for all Ss but was differentially more difficult for four-year-olds. Under the full report conditions, all Ss showed a parallel independent processing strategy as array size increased from one to two items, but four-year-olds did not apply this strategy as efficiently as older Ss. As array size increased from two to four items, only adults and eight-year-olds continued to show parallel independent processing, up to a limit. This age difference in processing strategv for the largest arrays may underlie age differences that have been found in short-term memory capacity.     

Recognition vs recall of visually vs acoustically confusable letter matrices

In an attempt to separate auditory and visual components in short-term memory, five subjects were exposed to letter matrices composed of six visually confusable letters, six acoustically confusable letters, or a mixture of the two, under two response conditions: recognition and recall. A 50-msec stimulus presentation was followed by a variable dark interval of 1, 250, 1,000, or 3,000 msec. In the recall condition, the interval was followed by a buzzer which signaled the subject to recall, in any order, as many letters as possible. In the recognition condition, the variable interval was followed by a second letter matrix which was either identical to the first matrix or differed from is by one letter. Subjects responded either "same" or "different." The results support the notion that the auditory component plays a major role in recall, whereas the visual component dominates in recognition.     

The effect of enactment upon sentence imitation in preschool children

Preschool children imitated two matched lists of sentences varying in length, in syntactic complexity, and in semantic complexity. Sentences on one list were acted out with toys prior to imitating them. For 3-year-olds, enactment increased retention of all sentential variables: number of words, number of frames, number of propositions, and syntax. For children younger than 3 years, enactment increased only the number of words retained, while for children older than 4 years, enactment had a minimal effect on all sentential variables. In a second experiment, prior enactment had long-term effects on the degree to which children's spontaneous stories about the toys resembled the previous sentences that they had been given to imitate. Long-term effects, however, did not extend to retention of syntax. Enactment appears to increase both young children's interest in a sentence imitation task and the amount of semantic encoding in which they engage. Its effect, however, is mediated by the degree of mastery of relevant linguistic rules.Some of these data were presented at the Biennial Meeting of the Society for Research in Child Development, Detroit, April 1983. The authors would like to thank Lorraine Chiasson, Judith Codd, and Susan Saba for their assistance with the data analysis.     

On the inhibitory nature of binocular rivalry suppression

During binocular rivalry the average duration of a suppression phase depends on the stimulus strength (e.g., contrast) of the input to the suppressed eye. To determine if a similar relationship exists between stimulus strength and the inhibitory effect of suppression on test probe detectability, a series of experiments was performed. Using two-alternative forced-choice procedures, increment detection thresholds were measured during phases of dominance and suppression. Results from three trained observers show that detection performance is significantly impaired during suppression by an amount that is independent of any difference in contrast between the rivalrous stimuli. These data indicate that the magnitude of the inhibitory effect of suppression is governed by a mechanism other than that which determines suppression duration.     

The development of sensitivity to biological motion in noise

We investigated developmental changes in sensitivity to biological motion by asking 6-year-olds, 9-year-olds, and adults (twenty-four in each group) to discriminate point-light biological motion displays depicting one of a variety of human movements from scrambled versions of the same displays. When tested without noise dots, participants at all ages performed near ceiling levels and no differences in accuracy were found among the three age groups. Age differences emerged in the second task, in which we used a staircase procedure to determine threshold values of the number of noise dots that could be tolerated in producing a percentage correct value corresponding to a d' value of 1.4. Sensitivity to biological motion improved linearly with age (p < 0.01), with 6-year-olds performing significantly more poorly than adults. This immature performance contrasts with adult-like accuracy by 4 years of age for sensitivity to global motion (Parrish et al, 2005 Vision Research 45 827-837). The comparison implies an immaturity at 6 years of age in the neural networks involved specifically in the processing of biological motion, networks that may include the superior temporal sulcus (STS).