Psychiatric Disorders in Clinical Genetics I: Addressing Family Histories of Psychiatric Illness

This is the first article of a two-part professional development series addressing genetic counseling for personal and family histories of psychiatric disorders. It is based on an Educational Breakout Session presented by the Psychiatric Special Interest Group of the National Society of Genetic Counselors at the 2006 Annual Education Conference. This article examines issues that arise in addressing family histories of psychiatric illness, while the second article in the series considers the generation and provision of individualized recurrence risks for psychiatric disorders. In this article we discuss the importance of managing uncertainty for affected individuals and their close family members who have been referred to genetics for a number of different indications. We then use four simulated cases to make recommendations about the scope and timing of discussions related to the psychiatric family history.     

Stereoscopic depth and the occlusion illusion

In the occlusion illusion, the visible portion of a partly occluded object appears larger than a physically identical nonoccluded region. Stereoscopic displays allowed for a direct test of the apparent-distance hypothesis. In Experiments 1A and 1B, we measured both the perceived size and the perceived depth of partly occluded targets when the binocular disparity of both targets and occluders was varied. Stereoscopic occlusion greatly increased perceived target size but not perceived target distance. A reduced illusion was still present when the target was stereoscopically in front of the abutting rectangle, however. Experiments 2A and 2B showed similar results, even when the occluding figures were illusory rectangles that formed no explicit T-junctions. Experiment 3 showed that an unexpected negative size illusion on control trials was primarily due to adaptation to the occlusion illusion on other trials. The present findings eliminate apparent-distance explanations of the occlusion illusion but are consistent with other hypotheses, such as partial modal completion and selective dimensional expansion.     

What Do We Know About Neuropsychological Aspects Of Schizophrenia?

Application of a neuropsychological perspective to the study of schizophrenia has established a number of important facts about this disorder. Some of the key findings from the existing literature are that, while neurocognitive impairment is present in most, if not all, persons with schizophrenia, there is both substantial interpatient heterogeneity and remarkable within-patient stability of cognitive function over the long-term course of the illness. Such findings have contributed to the firm establishment of neurobiologic models of schizophrenia, and thereby help to reduce the social stigma that was sometimes associated with purely psychogenic models popular during parts of the 20th century. Neuropsychological studies in recent decades have established the primacy of cognitive functions over psychopathologic symptoms as determinants of functional capacity and independence in everyday functioning. Although the cognitive benefits of both conventional and even second generation antipsychotic medications appear marginal at best, recognition of the primacy of cognitive deficits as determinants of functional disability in schizophrenia has catalyzed recent efforts to develop targeted treatments for the cognitive deficits of this disorder. Despite these accomplishments, however, some issues remain to be resolved. Efforts to firmly establish the specific neurocognitive/neuropathologic systems responsible for schizophrenia remain elusive, as do efforts to definitively demonstrate the specific cognitive deficits underlying specific forms of functional impairment. Further progress may be fostered by recent initiatives to integrate neuropsychological studies with experimental neuroscience, perhaps leading to measures of deficits in cognitive processes more clearly associated with specific, identifiable brain systems.     

Suppression effects on musical and verbal memory

Three experiments contrasted the effects of articulatory suppression on recognition memory for musical and verbal sequences. In Experiment 1, a standard/comparison task was employed, with digit or note sequences presented visually or auditorily while participants remained silent or produced intermittent verbal suppression (saying "the") or musical suppression (singing "la"). Both suppression types decreased performance by equivalent amounts, as compared with no suppression. Recognition accuracy was lower during suppression for visually presented digits than during that for auditorily presented digits (consistent with phonological loop predictions), whereas accuracy was equivalent for visually presented notes and auditory tones. When visual interference filled the retention interval in Experiment 2, performance with visually presented notes but not digits was impaired. Experiment 3 forced participants to translate visually presented music sequences by presenting comparison sequences auditorily. Suppression effects for visually presented music resembled those for digits only when the recognition task required sensory translation of cues.     

Validation of a clerical test using work samples

zWork simulation performance tests of filing and proofreading were the principal criteria in a validation study of a paper and pencil clerical selection test constructed by content-oriented methods; supervisory ratings were also used. Experiment 1 was a concurrent study using as subjects 59 provisional employees. Experiment 2 was a predictive study using as subjects 184 employees actually selected on the basis of test scores. In both studies, substantial correlations were found between scores on the selection test and performance on the work samples: Estimates of correlations in the original selection group ranged from .4 to .8. Correlations between the selection test and the supervisor ratings were significant in Experiment 1, but not in Experiment 2; even when significant, they were much lower than the correlations with the work samples. These results suggest the value of using work samples as criteria for validation studies. Implications for other validation efforts are considered.     

Myths as Instructions from Ancestors: The Example of Oedipus

The growing interest in dual-inheritance models of human evolution has focused attention on culture as a means by which ancestors transmitted acquired phenotypic characteristics to their descendants. The ability of cultural behaviors to be repeatedly transmitted from ancestors to descendants enables individuals to influence their descendant-leaving success over many more generations than are usually coclusive fitness. This essay proposes that traditional stories, or myths, can be seen as a way in which ancestors influence their descendant-leaving success by influencing the behavior of many generations of their descendants. The myth of Oedipus is used as an example of a traditional story aimed at promoting proper behavior and cooperation among kin. This interpretation of the Oedipus myth is contrasted with Freudian and structuralist interpretations.     

Measuring the effect of multiple eye fixations on memory for visual attributes.

Because of limited peripheral vision, many visual tasks depend on multiple eye fixations. Good performance in such tasks demonstrates that some memory must survive from one fixation to the next. One factor that must influence performance is the degree to which multiple eye fixations interfere with the critical memories. In the present study, the amount of interference was measured by comparing visual discriminations based on multiple fixations to visual discriminations based on a single fixation. The procedure resembled partial report, but used a discrimination measure. In the prototype study, two lines were presented, followed by a single line and a cue. The cue pointed toward one of the positions of the first two lines. Observers were required to judge if the single line in the second display was longer or shorter than the cued line of the first display. These judgments were used to estimate a length threshold. The critical manipulation was to instruct observers either to maintain fixation between the lines of the first display or to fixate each line in sequence. The results showed an advantage for multiple fixations despite the intervening eye movements. In fact, thresholds for the multiple-fixation condition were nearly as good as those in a control condition where the lines were foveally viewed without eye movements. Thus, eye movements had little or no interfering effect in this task. Additional studies generalized the procedure and the stimuli. In conclusion, information about a variety of size and shape attributes was remembered with essentially no interference across eye fixations.