Age-related changes in executive function: an event-related potential (ERP) investigation of task-switching

Older adults have difficulty when executive control must be brought on line to coordinate ongoing behavior. To assess age-related alterations in executive processing, task-switching performance and event-related potential (ERP) activity were compared in young and older adults on switch, post-switch, pre-switch, and no-switch trials, ordered in demand for executive processes from greatest to least. In stimulus-locked averages for young adults, only switch trials elicited fronto-central P3 components, indicative of task-set attentional reallocation, whereas in older adults, three of the four trial types evinced frontal potentials. In response-locked averages, the amplitude of a medial frontal negativity (MFN), a component reflecting conflict monitoring and detection, increased as a function of executive demands in the ERPs of the young but not those of the older adults. These data suggest altered executive processing in older adults resulting in persistent recruitment of prefrontal processes for conditions that do not require them in the young.     

Are average and symmetric faces attractive to infants? Discrimination and looking preferences

Young infants prefer to look at faces that adults find attractive, suggesting a biological basis for some face preferences. However, the basis for infant preferences is not known. Adults find average and symmetric faces attractive. We examined whether 5-8-month-old infants discriminate between different levels of averageness and symmetry in faces, and whether they prefer to look at faces with higher levels of these traits. Each infant saw 24 pairs of female faces. Each pair consisted of two versions of the same face differing either in averageness (12 pairs) or symmetry (12 pairs). Data from the mothers confirmed that adults preferred the more average and more symmetric versions in each pair. The infants were sensitive to differences in both averageness and symmetry, but showed no looking preference for the more average or more symmetric versions. On the contrary, longest looks were significantly longer for the less average versions, and both longest looks and first looks were marginally longer for the less symmetric versions. Mean looking times were also longer for the less average and less symmetric versions, but those differences were not significant. We suggest that the infant looking behaviour may reflect a novelty preference rather than an aesthetic preference.     

Development of and change in cognitive control: A comparison of children, young adults, and older adults

Cognitive control involves adjustments in behavior to conflicting information, develops throughout childhood, and declines in aging. Accordingly, developmental and age-related changes in cognitive control and response-conflict detection were assessed in a response-compatibility task. We recorded performance measures, pre-response time (pre-RT) activity and medial frontal negativity (MFN)—sequentially occurring, putative event-related potential (ERP) indexes, respectively, of cognitive control and response-conflict detection. When response conflict reached the highest levels by requiring incompatible responses on posterror trials, children and older adults showed the greatest performance decrements. ERPs indicated that young adults implemented control (pre-RT) and detected the increased conflict (MFN) only when that conflict was at the highest levels, whereas children and older adults did so at lower levels (e.g., posterror, compatible responses). Consequently, the developmental and age-related performance decrements observed here may be due to the undifferentiated and inefficient manner in which children and older adults recruited the processes associated with both cognitive control and response-conflict detection.     

Social and personal determinants of workplace aggression: Evidence for the impact of perceived injustice and the Type A Behavior Pattern

Four hundred fifty‐two employed persons rated the frequency with which they had been the victims of a wide range of aggressive actions at work. In addition, they also rated the frequency with which they themselves had aggressed against others in their workplaces. Three hypotheses were investigated: (1) covert forms of aggression, in which aggressors seek to conceal their identity from target persons, are significantly more frequent in workplaces than overt forms of aggression; (2) the greater the perceived injustice reported by employees, the greater their tendency to engage in workplace aggression; and (3) the higher individuals' scores on a measure of the Type A Behavior Pattern, the greater their reported frequency of engaging in various forms of workplace aggression. Results offered support for all three hypotheses. In addition, several demographic variables (participants' age and gender; the physical location of their workplaces) were also found to play a role in the occurrence of workplace aggression. Together, these findings were interpreted as underscoring the importance of establishing close conceptual links between research on workplace aggression and basic research on human aggression. Aggr. Behav. 25:281–296, 1999. © 1999 Wiley‐Liss, Inc.