Properties of context-driven control revealed through the analysis of sequential congruency effects.

The context specific proportion congruent (CSPC) effect refers to the reduction in the size of the congruency effect at locations with a high proportion of incongruent trials compared to locations with a high proportion of congruent trials. The CSPC effect is commonly taken as evidence for context-driven modulation of cognitive control. Current models of context-driven control suggest that variations in the efficiency of control across locations are due to variations in the occurrence of conflict across locations (context). Moreover, these models predict that control settings are updated on a trial-to-trial basis. In Experiment 1, we investigated this prediction. If variations in conflict drive variations in the efficiency of control, and these location-based control settings are updated on each trial, then the occurrence of conflict at one location should lead to more efficient processing when the location repeats, but not when the location switches. Consistent with this prediction, we observed a sequential congruency effect when the location repeats, but not when the location switches. In Experiment 2, we looked for evidence of sequential congruency effects within and between locations in a manipulation in which an equal proportion of congruent and incongruent trials appear at each location. In contrast to the results of Experiment 1, we observed sequential congruency effects both when location repeated and when location switched. Thus, location appears to be a salient dimension on which to implement control settings when it is used in conjunction with variations in the proportion of congruent and incongruent trials.

Limits on the generalizability of context-driven control.

Context-driven control refers to the fast and flexible weighting of stimulus dimensions that may be applied at the onset of a stimulus. Evidence for context-driven control comes from interference tasks in which participants encounter a high proportion of incongruent trials at one location and a high proportion of congruent trials at another location. Since the size of the congruency effect varies as a function of location, this suggests that stimulus dimensions are weighted differently based on the context in which they appear. However, manipulations of condition proportion are often confounded by variations in the frequency with which particular stimuli are encountered. To date, there is limited evidence for the context-driven control in the absence of stimulus frequency confounds. In the current paper, we attempt to replicate and extend one such finding [Crump, M. J. C., & Milliken, B. (2009). The flexibility of context-specific control: Evidence for context-driven generalization of item-specific control settings. The Quarterly Journal of Experimental Psychology, 62, 1523-1532]. Across three experiments we fail to find evidence for context-driven control in the absence of stimulus frequency confounds. Based on these results, we argue that consistency in the informativeness of the irrelevant dimension may be required for context-driven control to emerge.

When and why do old adults outsource control to the environment?

Old adults' tendency to rely on information present in the environment rather than internal representations has been frequently noted, but is not well understood. The fade-out paradigm provides a useful model situation to study this internal-to-external shift across the life span: Subjects need to transition from an initial, cued task-switching phase to a fade-out phase where only 1 task remains relevant. Old adults exhibit large response-time "fade-out costs," mainly because they continue to consult the task cues. Here we show that age differences in fade-out costs remain very large even when we insert between the task-switching and the fade-out phase 20 single-task trials without task cues (during which even old adults' performance becomes highly fluent; Experiment 1), but costs in old adults are eliminated when presenting an on-screen instruction to focus on the 1 remaining task at the transition point between the task-switching and fade-out phase (Experiment 2). Furthermore, old adults, but not young adults, also exhibited "fade-in costs" when they were instructed to perform an initial single-task phase that would be followed by the cued task-switching phase (Experiment 3). Combined, these results show that old adults' tendency to overutilize external support is not a problem of perseverating earlier-relevant control settings. Instead, old adults seem less likely to initiate the necessary reconfiguration process when transitioning from 1 phase to the next because they use underspecified task models that lack the higher-level distinction between those contexts that do and that do not require external support.

Contextual influences on the sequential congruency effect.

The sequential congruency effect (SCE) refers to the reduction in the size of the congruency effect following incongruent, relative to congruent, trials. Prior evidence indicated that the SCE does not generalize across tasks or different conflict-producing feature dimensions. We present results from a Stroop task showing that when the local list context is such that all colors and words appear in the same proportion of congruent trials, the SCE is present, but when those same items vary in the proportions congruent, the SCE is absent. We suggest that if stimuli are sufficiently consistent in the informativeness of their dimensions for the responses, individuals will attempt to track such information and weight the dimensions accordingly. In this way, the SCE reflects sequential adjustments to the weights given to individual stimulus dimensions in an attempt to track this information.

The effect of lexical frequency on spoken word recognition in young and older listeners.

When identifying spoken words, older listeners may have difficulty resolving lexical competition or may place a greater weight on factors like lexical frequency. To obtain information about age differences in the time course of spoken word recognition, young and older adults' eye movements were monitored as they followed spoken instructions to click on objects displayed on a computer screen. Older listeners were more likely than younger listeners to fixate high-frequency displayed phonological competitors. However, degradation of auditory quality in younger listeners does not reproduce this result. These data are most consistent with an increased role for lexical frequency with age.

Validated intraclass correlation statistics to test item performance models.

A new method, with an application program in Matlab code, is proposed for testing item performance models on empirical databases. This method uses data intraclass correlation statistics as expected correlations to which one compares simple functions of correlations between model predictions and observed item performance. The method rests on a data population model whose validity for the considered data is suitably tested and has been verified for three behavioural measure databases. Contrarily to usual model selection criteria, this method provides an effective way of testing under-fitting and over-fitting, answering the usually neglected question "does this model suitably account for these data?"

A corpus analysis of patterns of age-related change in conversational speech.

Conversational speech from over 300 speakers from 17 to 68 years of age was analyzed for age-related changes in the timing and content of spoken language production. Overall, several relationships between the lexical content, timing, and fluency of speech emerged, such that more novel and lower frequency words were associated with slower speech and higher levels of disfluencies. Speaker age was associated with slower speech and more filled pauses, particularly those associated with lexical selection. Increasing age, however, was also associated with longer utterances and greater lexical diversity. On balance, these analyses present a picture of age-related changes in speech performance that largely support data obtained from controlled laboratory studies. However, particular patterns of age-related change may be moderated in conversational situations.

Predicting conversion to dementia of the Alzheimer's type in a healthy control sample: the power of errors in Stroop color naming.

In the present study, we investigated which cognitive functions in older adults at Time A are predictive of conversion to dementia of the Alzheimer's type (DAT) at Time B. Forty-seven healthy individuals were initially tested in 1992-1994 on a trial-by-trial computerized Stroop task along with a battery of psychometric measures that tap general knowledge, declarative memory, visual-spatial processing, and processing speed. Twelve of these individuals subsequently developed DAT. The errors on the color incongruent trials (along with the difference between congruent and incongruent trials) and changes in the reaction time distributions were the strongest predictors of conversion to DAT, consistent with recent arguments regarding the sensitivity of these measures. Notably in the psychometric measures, there was little evidence of a difference in declarative memory between converters and nonconverters, but there was some evidence of changes in visual-spatial processing. Discussion focuses on the accumulating evidence suggesting a role of attentional control mechanisms as an early marker for the transition from healthy cognitive aging to DAT.

Age-related differences in communication and audience design.

This article reports an experiment examining the extent to which younger and older speakers engage in audience design, the process of adapting one's speech for particular addresses. Through an initial card-matching task, pairs of younger adults and pairs of older adults established common ground for sets of picture cards. Subsequently, the same individuals worked separately on a computer-based picture-description task that involved a novel partner-cuing paradigm. Younger speakers' descriptions to the familiar partner were shorter and were initiated more quickly than were descriptions to an unfamiliar partner. In addition, younger speakers' descriptions to the familiar partner exhibited a higher proportion of lexical overlap with previous descriptions than did descriptions to an unfamiliar partner. Older speakers showed no equivalent evidence for audience design, which may reflect difficulties with retrieving partner-specific information from memory during conversation.

Lexical competition and phonological encoding in young and older speakers.

The influence of age on word retrieval was investigated with a speeded picture naming study. Five hundred forty-one pictures were presented to young and older adults, and the influence of name agreement and name frequency was analyzed by multiple regression. The results showed that both name agreement and name frequency are significant predictors of picture naming performance in young and older adults. The results also suggest that older adults are more strongly influenced by name agreement than are young adults. These results indicate that competition during lexical selection may be a particularly age-sensitive stage in language production.

Observing the what and when of language production for different age groups by monitoring speakers' eye movements.

Research on adult age differences in language production has traditionally focused on either the production of single words or the properties of language samples. Older adults are more prone to word retrieval failures than are younger adults (e.g., ). Older adults also tend to produce fewer ideas per utterance and fewer left-branching syntactic structures (e.g., ). The use of eye movement monitoring in the study of language production allows researchers to examine word production processes in the context of multiword utterances, bridging the gap between behavior in word production studies and spontaneous speech samples. This paper outlines one view of how speakers plan and produce utterances, summarizes the literature on age-related changes in production, presents an overview of the published research on speakers' gaze during picture description, and recaps a study using eye movement monitoring to explore age-related changes in language production.

Outsourcing cognitive control to the environment: adult age differences in the use of task cues.

When an initial phase of cued task switching is followed by a phase of single-task trials, older adults show difficulties changing to the more efficient single-task mode of processing (Mayr & Liebscher, 2001). In Experiment 1, we show that these costs follow older adults' continued tendency to inspect task cues even though these provide no new information. In Experiment 2, we included a condition in which task cues were eliminated from the display after the task-switching phase. In this condition, older adults behaved the same as younger adults, suggesting that the presence of the task cue is critical for observing age differences while switching from a "high-control" to a "low-control" mode of processing. We discuss our results in terms of a life-span shift with regard to the reliance on internal versus external sources of information under conditions of high-control demands.

Analysis of group differences in processing speed: where are the models of processing?

Recently, Myerson, Adams, Hale, and Jenkins (2003) replied to arguments advanced by Ratcliff, Spieler, and McKoon (2000) about interpretations of Brinley functions. Myerson et al. (2003) focused on methodological and terminological issues, arguing that (1) Brinley functions are not quantile-quantile (QQ) plots of distributions of mean reaction times (RTs) across conditions; that the fact that the slope of a Brinley function is the ratio of the standard deviations of the two distributions of means has no implications for the use of slope as a measure of processing speed; that the ratio of slopes of RT functions for older and young subjects plotted against independent variables equals the Brinley function slope; and that speed-accuracy criterion effects do not account for slowing with age. We reply by showing that Brinley functions are plots of quantiles against quantiles; that the slope is best estimated by the ratio of standard deviations because there is variability in the distributions of mean RTs for both older and young subjects; that the interpretation of equality of the slopes Brinley functions and plots of RTs against independent variables in terms of processing speed is model dependent; and that speed-accuracy effects in some, but not all, experiments are solely responsible for Brinley slopes greater than 1. We conclude by reiterating the point that was not addressed in Myerson et al. (2003), that the goal of research should be model-based accounts of processing that deal with correct and error RT distributions and accuracy.

Visual word recognition of single-syllable words.

Speeded visual word naming and lexical decision performance are reported for 2428 words for young adults and healthy older adults. Hierarchical regression techniques were used to investigate the unique predictive variance of phonological features in the onsets, lexical variables (e.g., measures of consistency, frequency, familiarity, neighborhood size, and length), and semantic variables (e.g. imageahility and semantic connectivity). The influence of most variables was highly task dependent, with the results shedding light on recent empirical controversies in the available word recognition literature. Semantic-level variables accounted for unique variance in both speeded naming and lexical decision performance, level with the latter task producing the largest semantic-level effects. Discussion focuses on the utility of large-scale regression studies in providing a complementary approach to the standard factorial designs to investigate visual word recognition.