Effects of Data Noise on Statistical Judgement

People made forecasts from graphically presented time series. Series were sinusoids overlaid by a zero or positive linear trend and a zero, low, moderate, or high level of noise. Forecasting performance was affected by both these variables. However, it did not correlate with ability to identify the trend and correlated significantly with ability to detect the sinusoidal pattern only when series were noise-free. A second experiment showed that the effect of data noise was not influenced by the number of forecasts that people made from a series. These findings are consistent with the view that data noise does not affect the way that forecasts are made but that it impairs them for two reasons. First, it renders the anchor-and-adjust heuristics underlying them less effective. Second, it causes people to add more noise to their judgements in their attempts to make them representative of the data.     

Depression at 3 Months Poststroke in the Elderly: Predictors and Indicators of Prevalence

The prevalence and determinants of depression in 79 elderly patients were assessed at 3 months poststroke. Predictor variables included gender, age, history of previous stroke, and hemispheric location of stroke. Indicator variables included two measures of physical functioning and seven aspects of cognitive functioning. Results indicated that 56% of patients had impairment in activities of daily living, and 39% reported clinically significant levels of depression. Prevalence of cognitive impairment ranged from 31% on a measure of basic cognitive functioning, through to 89% on a measure of complex attention. The results from a hierarchical multiple regression analysis showed that the combination of predictor and indicator variables explained 53% of the variance in depression scores. The three individual variables of history of previous stroke, physical functioning, and simple attention all made significant unique contributions to the variance in depression scores. The contribution of these findings to the ongoing debate concerning lesion location and poststroke depression is discussed.     

Modifying driver behaviour with passenger feedback

A feedback programme was employed to help drivers improve their safety behaviour based on the idea that particular types of driver error result from contingency traps as defined by Fuller [Journal of Applied Behaviour Analysis, 24 (1991) 73]. Two drivers and their single respective passengers participated. For each driver, repeated in-car observations were made of four unsafe driving behaviours. Two of these were sequentially targeted in the behavioural intervention that involved the passengers providing informational feedback to their driver. Both drivers showed a marked improvement across the targeted behaviours. The study demonstrated the applicability of behaviour analysis to the traffic domain and the efficacy of individual feedback as a behavioural tool for positive behaviour modification.     

The stroop effect: Failure to focus attention or failure to maintain focusing?

Subjects matched the position (high or low) of a first stimulus with either the position or the meaning of a word (HI or LO) presented after an interstimulus interval (ISI). The form of the first stimulus (X or O) varied randomly within trial blocks and specified the relevant feature (meaning or position) of the second stimulus to the subject. When the relevant feature was meaning, Stroop interference from the second stimulus position was observed. This interference decreased as ISI increased. At the longest ISI, it was eliminated completely. A number of explanations for these effects are discussed and then tested in two further matching experiments. In a fourth experiment a similar decrease in interference was observed. These reductions in interference with increase in ISI appear to represent the development of attentional focusing on the relevant feature of the second stimulus. Stroop interference may occur in experiments where the relevant attribute is constant because of a difficulty associated with repeated focusing on the same attribute.     

Spontaneous and learned turning behaviour in food- or water-restricted hooded rats

Some laboratory studies have suggested that whereas food restriction in animals leads to response alternation (behavioural flexibility), water restriction induces perseverative, stereotyped responding. Hooded rats, restricted to 1 hour per day access to either food or water, were tested on a radial-arm maze (using a procedure that eliminates algorithmic response strategies), for alternation in a 3-arm maze (both when the maze was familar and unfamilar, and with or without differential reward) and a 2-choice maze in which some animals were taught to alternate direction of turn, and others to perseverate. Both groups performed the radial-arm maze task competently and spontaneously alternated at a high rate. In the learned task, food-restricted rats were slower than water-restricted to reverse a consistent direction of turn; in the alternation condition, water-restricted rats developed a temporary, but strong, directional bias when making their first choice each day. Water-restricted subjects took water more readily than food-restricted took food when initially introduced to the apparatuses, but there was no consistent difference in motivation in the two conditions. The results provide little support for the notion that distinct cognitive-motivational states or behavioural strategies are induced by food- and water-restriction.     

Moral reasoning,emotion understanding,and callous-unemotional traits in early-to-middle childhood

Relatively little is known about features of moral reasoning among young children with callous-unemotional (CU) traits (e.g., lack of guilt and empathy). This study tested associations between CU traits and emotion attributions (i.e., identification of others’ emotional states) and justifications (i.e., explanations for those emotional states), across social scenarios involving discreet versus salient distress cues. The participants were boys aged 6-to-10 years (N = 50; M_age = 7 years 7 months), who were interviewed about 12 hypothetical scenarios (eight with discreet and four with salient distress cues). Regression models indicated that CU traits, in interaction with high levels of antisocial behaviour, were associated with reduced emotion attributions of fear in discreet but not salient immoral scenarios. Higher CU traits were also associated with reduced justifications referencing others’ welfare in discreet scenarios, and increased references to action-orientated justifications in salient scenarios. These findings suggest that CU traits are associated with early moral reasoning impairments and that salience of distress may be important to these processes.     

Presentation modality affects false memory

Roediger and McDermott (1995) rejuvenated interest in Deese’s (1959) paradigm for producing reliable intrusions and false alarms. Using this paradigm in three experiments, we demonstrated that visual study presentation dramatically reduces the rate of false memories. Only auditory study presentation resulted in equal production of studied and critical items. Correct recall and recognition were unaffected. The suggestion that visual presentation provides a means for discriminating between false and true memories was supported by Experiment 3: Pleasantness rating of study items significantly reduced the creation of false memories regardless of modality.