The effects of task and practice on search for invisibly displaced objects

The ability to successfully search for an invisibly displaced object is frequently assumed to relate to the emergence of mental representation at around 2 years of age. However, little is known about what is actually being measured in the typical “stage 6” object permanence search task. Two studies examined the effects of task factors and practice on invisible displacements and systematic search tasks to show that simple variations in ways of hiding an object change the child's ability to find it. Experiment 1 compared two common methods of presenting invisible displacements items to 36 children, approximately 2 years of age. One task was significantly easier than the other, despite the fact that they contained identical items that varied only in their order of presentation. Experiment 2 tested the effects of short-term practice on 18- and 24-month-olds' success on invisible displacements trials and on two systematic search tasks. Results indicate that too little practice inhibited performance in 18-month-olds, but that practice beyond an optimum level did not further affect their scores. In contrast, 24-month-olds continued to benefit from increased practice until they reached the maximum possible score. The findings are interpreted to mean that invisible displacements tasks may require only sensorimotor search strategies rather than representation. The findings also have implications for (a) research that attempts to relate object permanence to other variables and (b) programs that use object permanence as an assessment or screening measure.     

Identification of Nearly Fatal Suicide Attempts: Self-Inflicted Injury Severity Form

The Self-inflicted Injury Severity Form (SIISF) was developed as an epidemiological research tool for identifying individuals in hospital emergency departments who have life-threatening self-inflicted injuries. Data were collected from 715 patients with self-inflicted injuries in two large hospitals. In 295 of these cases, a second set of data was independently collected for assessment of interrater reliability. Validity was assessed by comparing the SIISF results with simultaneously collected Risk—Rescue Ratings. Assessment of interrater reliability found that only 2.4% of physicians disagreed on the suicide method used. The kappa statistic for method used was .94, indicating excellent agreement. The SIISF was found to distinguish between severe and less severe injuries. Thus, it appears to provide a simple method to distinguish patients who have life-threatening self-inflicted injuries.