Representation of memory for order of mental operations in cognitive tasks

Recent research shows that people learning a cognitive task acquire a memory for the order of operations applied, independent of the data to which those operations were applied. We designed two experiments to show how this sequence memory is represented. Experiment 1 compared predictions based on 3 possible sequence representation methods: composition, dyad transition, and associative chain. Latency and error results from a simple sequential task supported the associative chain representation. The associative links between operations presumably enhance performance by priming subsequent operations but do not operate in an all-or-none fashion. Experiment 2 explored whether transfer items that matched the first 2 rules and first 3 elements of a training item could bias participants toward executing a composed production learned during training. Latency and undetected error results were consistent with an associative chain representation but not with additional predictions made by the composition representation. These two experiments support the representation of operation sequences in memory as an associative chain.     

The structure of language abilities at 4 years: a twin study

Normal language development was studied in 310 pairs of 4-year-old twins born in the United Kingdom in 1994. Twins were assessed individually in their homes on a diverse battery of language and nonverbal measures. Rotated factor analyses indicated the presence of a general Language factor (L) as well as a general Nonverbal (NV) factor. Moderate genetic influence was found for both L and NV abilities. Bivariate genetic analysis estimated a genetic correlation of .63 between L and NV abilities, implying that over half of the genetic influence on L overlaps with genetic influence on NV. These results suggest that at age 4, genetic influences on individual differences in language overlap substantially with genetic influences on individual differences in other cognitive abilities, although perhaps less so than later in development.     

Strategic attention deployment for delay of gratification in working and waiting situations

Two studies examined whether the detrimental effects of attention to rewards on delay of gratification in waiting situations holds-or reverses-in working situations. In Study 1, preschoolers waited or worked for desired delayed rewards. Delay times increased when children worked in the presence of rewards but, as predicted, this increase was due to the distraction provided by the work itself. not because attention to rewards motivated children to sustain work. Analysis of spontaneous attention deployment showed that attending to rewards reduces delay time regardless of the working or waiting nature of the task. Fixing attention on rewards was a particularly detrimental strategy regardless of the type of task. Study 2 showed that when the work is not engaging, however, attention to rewards can motivate instrumental work and facilitate delay of gratification as long as attention deployment does not become fixed on the rewards.     

GROUP FORAGING SENSITIVITY TO PREDICTABLE AND UNPREDICTABLE CHANGES IN FOOD DISTRIBUTION: PAST EXPERIENCE OR PRESENT CIRCUMSTANCES?

The ideal free distribution theory (Fretwell & Lucas, 1970) predicts that the ratio of foragers at two patches will equal the ratio of food resources obtained at the two patches. The theory assumes that foragers have "perfect knowledge" of patch profitability and that patch choice maximizes fitness. How foragers assess patch profitability has been debated extensively. One assessment strategy may be the use of past experience with a patch. Under stable environmental conditions, this strategy enhances fitness. However, in a highly unpredictable environment, past experience may provide inaccurate information about current conditions. Thus, in a nonstable environment, a strategy that allows rapid adjustment to present circumstances may be more beneficial. Evidence for this type of strategy has been found in individual choice. In the present experiments, a flock of pigeons foraged at two patches for food items and demonstrated results similar to those found in individual choice. Experiment 1 utilized predictable and unpredictable sequences of resource ratios presented across days or within a single session. Current foraging decisions depended on past experience, but that dependence diminished when the current foraging environment became more unpredictable. Experiment 2 repeated Experiment I with a different flock of pigeons under more controlled circumstances in an indoor coop and produced similar results.     

Garner and congruence effects in the speeded classification of bimodal signals

The role of attention in speeded Garner classification of concurrently presented auditory and visual signals was examined in 4 experiments. Within-trial interference (i.e., congruence effects) occurred regardless of the attentional demands of the task. Between-trials interference (i.e., Garner interference) occurred only under conditions of divided attention when making judgments about auditory signals. Of importance, the data show congruence effects in the absence of Garner interference. Such a pattern has been rarely reported in studies of the classification of purely visual stimuli and contradicts theoretical accounts asserting that the effects share a common locus. The data question the notion that Garner classification reveals fundamental insights about the nature of the perceptual processing of bimodal stimuli.     

Ordinary physical punishment: is it harmful? Comment on Gershoff (2002)

E. T. Gershoff (2002) reviewed processes that might mediate and contexts that might moderate the associations between corporal punishment (CP) and child behaviors and provided an account of the methodological weaknesses of the research reviewed in her meta-analyses. In this examination of Gershoff, the authors argue that the biases and confounds in the meta-analyses further limit any causal inferences that can be drawn concerning the detrimental "effects" of CP on associated child behaviors. The authors suggest that undesirable child outcomes are associated with CP because the construct marks inept harsh parenting and conclude that although the harmful effects of physical abuse and other extreme punishments are clear, a blanket injunction against spanking is not justified by the evidence presented by Gershoff.     

Preference and resistance to change in concurrent variable-interval schedules

Pigeons were trained on a multiple schedule in which separate concurrent schedules were presented in the two components of the schedule. During one component, concurrent variable-interval 40-sec variable-interval 80-sec schedules operated. In the second component, concurrent variable-interval 40-sec variable-interval 20-sec schedules operated. After stable baseline performance was obtained in both components, extinction probe choice tests were presented to assess preference between the variable-interval 40-sec schedules from the two components. The variable-interval 40-sec schedule paired with the variable-interval 80-sec schedule was preferred over the variable-interval 40-sec schedule paired with the variable-interval 20-sec schedule. The subjects were also exposed to several resistance-to-change manipulations: (1) prefeeding prior to the experimental session, (2) a free-food schedule added to timeout periods separating components, and (3) extinction. The results indicated that preference and resistance to change do not necessarily covary.     

Strong cues are not necessarily weak: Thomson and Tulving (1970) and the encoding specificity principle revisited

Performance on tests in which there is control over reporting (e.g., cued recall with the option to withhold responses) can be characterized by four parameters: free- and forced-report retrieval (correct responses retrieved from memory when the option to withhold responses is exercised and when it is not, respectively), monitoring (discrimination between correct and incorrect potential responses), and report bias (willingness to report responses). Typically, researchers do not examine all these components in cued-test performance; blanks are sometimes counted the same as errors, meaning that the (free-report) performance index is contaminated with report bias and monitoring ability. In this research, a two-stage testing procedure is described that allows measures of free- and forced-report retrieval, monitoring, and bias to be derived from the original encoding specificity experiments (Thomson & Tulving, 1970). The results show that their cue-reinstatement manipulation affected free-report retrieval, but once report bias and monitoring effects were removed by forcing output, retrieval was unaffected.     

Age differences in overlapping-task performance: evidence for efficient parallel processing in older adults

Two psychological refractory period (PRP) experiments were conducted to examine overlapping processing in younger and older adults. A shape discrimination task (triangle or rectangle) for Task 1 (T1) and a lexical-decision task (word or nonword) for Task 2 (T2) were used. PRP effects, response time for T2 increasing as stimulus onset synchrony (SOA) decreased, were obtained for both age groups. The effect of word frequency on T2 was smaller at the short SOA than at the long SOA, reflecting slack effects, which were larger for older than younger adults in both experiments. These results suggest that older adults can perform lexical access of T2 in parallel with the processing of T1 at least as efficiently as younger adults.