Stimulus–response translation in manual and vocal modality: Is age‐related slowing influenced by changes in working memory functioning?

In some conditions, age‐related slowing rates are higher for manual than for vocal responses. The interaction between age and response modality was examined in four experiments in which the performance of younger (M = 22.6 years) and older (M = 70.8 years) adults was compared under various stimulus–response mapping rules. The interaction effect was not observed in a simple localisation task on which the manual modality had an advantage in both age groups (Experiment 1). When congruence between stimulus and response was reduced (Experiment 2), manual responses were disproportionately slowed in older participants. In conceptual and size comparison tasks (Experiment 3), the age‐by‐modality effect was not influenced by working memory load during the interval between the first and the second stimulus presentation. In an identification task, age‐related slowing effects were less when responses were spoken names than when nonwords were used as labels (Experiment 4). These results indicate that older participants experience a specific difficulty in activating arbitrary S–R mapping rules during executive control.     

Do response modality effects support multiprocessor models of divided attention?

Some studies have suggested that dual-task interference is greatly reduced when tasks requiring very different types of responses (e.g., manual and vocal) are combined. However, in those studies, the order of stimuli varied unpredictably. In Experiments 1 and 2, variable stimulus order greatly inflated interference between two manual tasks, whereas interference between a manual and a vocal task was only slightly exacerbated. However, central interference (the psychological refractory period) persisted even with the manual/vocal combination. Selection of 2 manual responses with unknown stimulus order may require a special strategy to preclude intertask intrusion errors. Experiment 3 demonstrated that such errors could be provoked with speed stress. Together, these results reconcile response modality effects with the response selection bottleneck model for dual-task interference (once it is suitably amended).     

On the Nature of the Probe Reaction-Time Task to Uncover the Attentional Demands of Movement

McLeod (1980) reported some findings which showed that no phase of a movement was more attention-demanding than the other phases, contrary to all the results previously reported (e.g., Ells, 1973; Glencross, 1980). However, McLeod used a paradigm in which the two tasks were serial. Each task consisted of a series of 50 reaction time (RT) trials and/or 50 aiming movement trials. In addition to this, the interval of time between a response and the following signal within each series was constant. In order to try to replicate McLeod’s findings, two experiments were conducted in which the response-signal interval was manipulated. The hypothesis was that time certainty associated with a constant interval would facilitate the allocation of time and would thus artificially reduce the interference between tasks. In Experiment I, manual responses were used for the RT task; in Experiment II, they were vocal. Manipulation of the response-signal interval does not change one of the conclusions reached by McLeod: when the RT task involves vocal responses and the results on the RT task are analyzed in terms of response rather than stimulus arrival during the movement, then there is no phase of the movement which is more attention-demanding than the other phases. However, the results of Experiment II in which both the vocal RT task and the movement task significantly deteriorated in the dual-task condition were taken as an indication that the movement studied involved central attentional demands.     

The Simon effect in vocal responses

The Simon effect refers to the finding that faster responses are made to non-spatial stimulus features (e.g., color) when the positions of stimulus and response correspond than when they do not correspond. The usual explanation is that a spatial stimulus code automatically activates a corresponding spatial response code. Recently, however, the Simon effect has also been observed in vocal responses. The present study investigated the properties of Simon effects in the vocal modality. Experiment 1 compared horizontal and vertical Simon effects in vocal responses and found similar patterns of sequential modulations, but different time-courses. Yet the observed results are similar to those described in the literature for manual Simon effects. Experiments 2 and 3 used a dual-task procedure to investigate the impact of manual response codes on the encoding of irrelevant location and the initiation of vocal responses, respectively. Results suggest close links between manual response codes and conceptually corresponding vocal response codes.     

A response-discrimination account of the Simon effect

Simon effects might partly reflect stimulus-triggered response activation. According to the response-discrimination hypothesis, however, stimulus-triggered response activation shows up in Simon effects only when stimulus locations match the top-down selected spatial codes used to discriminate between alternative responses. Five experiments support this hypothesis. In Experiment 1, spatial codes of each response differed by horizontal and vertical axis position, yet one axis discriminated between alternative responses, whereas the other did not. Simon effects resulted for targets on discriminating axes only. In Experiment 2, both spatial axes discriminated between responses, and targets on both axes produced Simon effects. In Experiment 3, Simon effects resulted for a spatial choice-reaction task but not for a go/no-go task. Even in the go/no-go task, a Simon effect was restored when a two-choice reaction task preceded the go/no-go task (Experiment 4) or when participants initiated trials with responses spatially discriminated from the go response (Experiment 5).     

On the nature of the probe reaction-time task to uncover the attentional demands of movement

McLeod (1980) reported some findings which showed that no phase of a movement was more attention-demanding than the other phases, contrary to all the results previously reported (e.g., Ells, 1973; Glencross, 1980). However, McLeod used a paradigm in which the two tasks were serial. Each task consisted of a series of 50 reaction time (RT) trials and/or 50 aiming movement trials. In addition to this, the interval of time between a response and the following signal within each series was constant. In order to try to replicated McLeod's findings, two experiments were conducted in which the response-signal interval was manipulated. The hypothesis was that time certainty associated with a constant interval would facilitate the allocation of time and would thus artificially reduce the interference between tasks. In Experiment 1, manual responses were used for the RT task; in Experiment II, they were vocal. Manipulation of the response-signal interval does not change one of the conclusions reached by McLeod: when the RT task involves vocal responses and the results on the RT task are analyzed in terms of response rather than stimulus arrival during the movement, then there is no phase of the movement which is more attention-demanding than the other phases. However, the results of Experiment II in which both the vocal RT task and the movement task significantly deteriorated in the dual-task condition were taken as an indication that the movement studied involved central attentional demands.     

Role of multiple resources in predicting time-sharing efficiency: evaluation of three workload models in a multiple-task setting

The goal of our study was to assess the validity of the assumptions underlying three prominent workload models: the Time-Line Analysis and Prediction workload model (Parks & Boucek, 1989), the VACP workload model (Aldrich, Szabo, & Bierbaum, 1989), and the W/INDEX model (North & Riley, 1989). Sixteen subjects flew a low-fidelity flight simulation. Subjects were required to perform a two-axis tracking task, a concurrent visual-monitoring task, and a discrete decision task. The decision task had 16 variations defined by two levels on each of the following dimensions: input modality (visual vs. auditory), processing code (spatial vs. verbal), difficulty (easy vs. hard), and response modality (manual vs. voice). Dual-task costs were found only for the tracking task. The tracking data were then analyzed using two approaches: a traditional analysis of variance (ANOVA) and a correlational analysis of tracking performance versus model predictions. The ANOVA revealed that performance on the tracking task was better when the concurrent decision task was responded to vocally and was easy. Input modality and processing code of the concurrent decision task had no significant effect on tracking performance. The correlational analysis was used to evaluate each of the three models, to determine what features were responsible for improving the models' fit, and to compare their performance with a pure time-line model that makes no multiple-resource assumptions. All three models did a good job of predicting variance between experimental conditions, accounting for between 56% and 84% of the variance in our data and between 10% and 40% of an earlier data set. Different features of each model that affect the fit are then discussed. We conclude that it is important for models to retain a multiple-resource coding, although the best features of that coding remain to be determined. Coding tasks by their demand level appears to be less critical.     

Interference effects of stimulus–response modality pairings in dual tasks and their robustness

Recent evidence suggests that the degree of interference in dual-task situations depends crucially on the pairings of input- and output modalities of the two component tasks with increased dual-task costs for modality incompatible (i.e., visual–vocal and auditory–manual) compared to modality compatible (i.e., visual–manual and auditory–vocal) dual tasks. These effects of modality pairings in dual tasks have been related to the overlap of non-preferred processing pathways in modality incompatible tasks. Until now, modality compatibility has not yet been related to other sources of interference in a dual-task context, such as stimulus–response (S–R) compatibility or crosstalk. In the present study, we conducted two experiments using the paradigm of the psychological refractory period (PRP) to test the effects of S–R compatibility and crosstalk on the effects of modality compatibility in temporally overlapping task situations. Experiment 1 revealed an overadditive interaction between stimulus onset asynchrony and modality compatibility for tasks with S–R compatible mappings, indicating that modality compatibility effects are present in different task situations, even when S–R mappings are otherwise compatible. In Experiment 2, we aimed at pinpointing the boundaries of the effects of modality compatibility in dual-task situations. We showed that additional sources of dual-task interference in a modality compatible dual task could overwrite the pronounced PRP effect previously shown for modality incompatible tasks. Taken together, these data provide new evidence that the specific types of stimulus–response modality pairings are an additional factor that might interact with other sources of interference in dual-task situations.     

Sustained attention in language production: An individual differences investigation

Whereas it has long been assumed that most linguistic processes underlying language production happen automatically, accumulating evidence suggests that these processes do require some form of attention. Here we investigated the contribution of sustained attention: the ability to maintain alertness over time. In Experiment 1, participants’ sustained attention ability was measured using auditory and visual continuous performance tasks. Subsequently, employing a dual-task procedure, participants described pictures using simple noun phrases and performed an arrow-discrimination task while their vocal and manual response times (RTs) and the durations of their gazes to the pictures were measured. Earlier research has demonstrated that gaze duration reflects language planning processes up to and including phonological encoding. The speakers’ sustained attention ability correlated with the magnitude of the tail of the vocal RT distribution, reflecting the proportion of very slow responses, but not with individual differences in gaze duration. This suggests that sustained attention was most important after phonological encoding. Experiment 2 showed that the involvement of sustained attention was significantly stronger in a dual-task situation (picture naming and arrow discrimination) than in simple naming. Thus, individual differences in maintaining attention on the production processes become especially apparent when a simultaneous second task also requires attentional resources.     

Modulating the masked congruence priming effect with the hands and the mouth

The authors report a series of experiments in which they use the masked congruence priming paradigm to investigate the processing of masked primes in the manual and verbal response modalities. In the manual response modality, they found that masked incongruent primes produced interference relative to both congruent and neutral primes. This finding, which replicates the standard finding in the masked congruence priming literature, is presumed to reflect the conflict that arises between two incompatible responses and, thus, to index the extent of processing of the masked prime. Somewhat surprisingly, when participants were asked to respond verbally in the same task, masked incongruent primes no longer produced interference, but masked congruent primes produced facilitation. These findings are surprising because they suggest that the processing of nonconsciously perceived primes extends to the response level in the manual, but not verbal, response modality. The authors propose that the modulation of the masked congruence priming effect by response modality is due to verbal, but not manual, responses being mediated by the lexical-phonological production system.     

Between-task transfer of learning from spatial compatibility to a color stroop task

Responses to a relevant stimulus dimension are faster and more accurate when the stimulus and response spatially correspond compared to when they do not, even though stimulus position is irrelevant (Simon effect). It has been demonstrated that practicing with an incompatible spatial stimulus-response (S-R) mapping before performing a Simon task can eliminate this effect. In the present study we assessed whether a learned spatially incompatible S-R mapping can be transferred to a nonspatial conflict task, hence supporting the view that transfer effects are due to acquisition of a general "respond to the opposite stimulus value" rule. To this aim, we ran two experiments in which participants performed a spatial compatibility task with either a compatible or an incompatible mapping and then transferred, after a 5 min delay, to a color Stroop task. In Experiment 1, responses were executed by pressing one of two keys on the keyboard in both practice and transfer tasks. In Experiment 2, responses were manual in the practice task and vocal in the transfer task. The spatially incompatible practice significantly reduced the color Stroop effect only when responses were manual in both tasks. These results suggest that during practice participants develop a response-selection strategy of emitting the alternative spatial response.     

Searching working memory for the source of dual-task costs

Dual-task costs depend on the specific pairings of stimulus and response modalities. Such findings are analogous to domain-specific effects in the working memory (WM) literature, in which items compete for limited capacity when they involve related types of information. The present study explicitly examines the relationship between modality-pairing effects on dual-task costs and domain-specificity effects on WM capacity. Participants maintained a sequence of either locations or tones in WM, and then performed a choice reaction time task in which they responded either vocally or manually. The stimuli for the choice reaction time task were held constant, but its response modality affected the interference observed in WM: vocal responses interfered with WM for tones and manual responses interfered with WM for locations. These findings indicate that response selection engages domain-specific WM processes and that interference within these processes may account for modality-pairing effects.     

Differential components of the manual and vocal Stroop tasks

In this study, four components of the Stroop effect were examined for manual word and vocal responses. The components were lexical, semantic relatedness, semantic relevance, and response set membership. The results showed that all four components were present in the vocal response task. However, in the manual word response task, the only component that produced significant interference on its own was response set membership. These results do not support predictions made by recent translation models (see W. R. Glaser & M. O. Glaser [1989] and Sugg & McDonald [1994]). A possible solution was suggested that located two sites for Stroop interference. The lexical, semantic relatedness, and semantic relevance effects were located in the lexical system, whereas the response set membership effect was located at a response selection stage.     

Response facilitation and inhibition in manual, vocal, and oculomotor performance: evidence for a modality-unspecific mechanism

In 2 experiments (N = 10, Experiment 1; N = 16, Experiment 2), the authors investigated whether evidence for response facilitation and subsequent inhibition elicited by masked prime stimuli can be observed for output modalities other than manual responding. Masked primes were followed by target stimuli that required a 2-choice manual, saccadic, or vocal response. Performance was measured for compatible trials in which primes and targets were identical and for incompatible trials in which they were mapped to opposite responses. When primes were presented centrally, performance benefits were obtained for incompatible trials; whereas for peripherally presented primes, performance benefits were found in compatible trials. That pattern of results was obtained for manual responses and for saccadic eye movements (Experiment 1), demonstrating that those effects are not mediated by specialized dorsal pathways involved in visuomanual control. An analogous pattern of effects was found when manual and vocal responses were compared (Experiment 2). Because vocal responding is controlled by the inferotemporal cortex, that result shows that prime-target compatibility effects are not primarily mediated by the dorsal stream, but appear to reflect modality-unspecific visuomotor links that allow rapid activation of motor responses that may later be subject to inhibition.     

Vocal and manual response latencies to bilateral and unilateral tachistoscopic letter displays

Bilateral rows of eight letters and unilateral rows of four letters were presented in randomized sequences for 100 ms. Subjects were required to recall all letters in a trial (Experiment I); recall letters from one hemifield cued at exposure (Experiment II); recognize a single letter, making a vocal response (Experiment III); recognize a single letter, making a manual response (Experiment IV). In Experiments I, II and III, identification errors were fewer and vocal response latencies were faster for RVF stimuli, except in the bilateral condition on Experiment I; in Experiment IV manual response latencies were the same, for left and right, bilateral and unilateral conditions. Collectively, the results could not be satisfactorily accounted for by any one hypothesis: report-order, trace-scanning, or cerebral dominance. The relative contribution of each process to the laterality effect was discussed.     

Response Facilitation and Inhibition in Manual,Vocal, and Oculomotor Performance: Evidence for a Modality-Unspecific Mechanism

In 2 experiments (N = 10, Experiment 1; N = 16, Experiment 2), the authors investigated whether evidence for response facilitation and subsequent inhibition elicited by masked prime stimuli can be observed for output modalities other than manual responding. Masked primes were followed by target stimuli that required a 2-choice manual, saccadic, or vocal response. Performance was measured for compatible trials in which primes and targets were identical and for incompatible trials in which they were mapped to opposite responses. When primes were presented centrally, performance benefits were obtained for incompatible trials; whereas for peripherally presented primes, performance benefits were found in compatible trials. That pattern of results was obtained for manual responses and for saccadic eye movements (Experiment 1), demonstrating that those effects are not mediated by specialized dorsal pathways involved in visuomanual control. An analogous pattern of effects was found when manual and vocal responses were compared (Experiment 2). Because vocal responding is controlled by the inferotemporal cortex, that result shows that prime-target compatibility effects are not primarily mediated by the dorsal stream, but appear to reflect modality-unspecific visuomotor links that allow rapid activation of motor responses that may later be subject to inhibition.     

Context influences decision-making in boys with attention-deficit/hyperactivity disorder: A comparison of traditional and novel choice-impulsivity paradigms

Attention-deficit/hyperactivity disorder (ADHD) is characterized by an impaired ability to maintain attention and/or hyperactivity/impulsivity. Impulsivity is frequently defined as the preference for small, immediate rewards over larger, delayed rewards, and has been associated with a variety of negative outcomes such as risky behavior and academic difficulty. Extant studies have uniformly utilized the traditional paradigm of presenting two response choices, which limits the generalization of findings to scenarios in which children/adolescents are faced with dichotomous decisions. The current study is the first to examine the effect of manipulating the number of available response options on impulsive decision-making in boys with and without ADHD. A total of 39 boys (ADHD = 16, typically developing [TD] = 23) aged 8–12 years completed a traditional two-choice impulsivity task and a novel five-choice impulsivity task to examine the effect of manipulating the number of choice responses (two vs five) on impulsive decision-making. A five-choice task was utilized as it presents a more continuous array of choice options when compared to the typical two-choice task, and is comparable given its methodological similarity to the two-choice task. Results suggested that boys with ADHD were significantly more impulsive than TD boys during the two-choice task, but not during the five-choice task. Collectively, these findings suggest that ADHD-related impulsivity is not ubiquitous, but rather dependent on variation in demands and/or context. Further, these findings highlight the importance of examining ADHD-related decision-making within the context of alternative paradigms, as the exclusive utilization of two-choice tasks may promote inaccurate conceptualizations of the disorder.     

Costs and benefits of strategy construction in a speeded discrimination task

The costs and benefits of constructing and utilizing a strategy for performing a speeded discrimination task were assessed in terms of time and mental resources. The strategy involved using information about the position a word occupied in order to respond to its identity more rapidly. The resources used to construct and utilize the strategy were assessed from responses to probes presented at various times during the task. In Experiment 1, the probe required a manual response, whereas in Experiment 2, the probe required a vocal response. Strategy construction interfered with the probe task in Experiment 1 but not in Experiment 2, suggesting that strategy construction required resources specific to the manual response system. There was also some evidence that strategy construction required general resources, but the evidence for specific resources was much stronger. The findings are consistent with our previous ideas about how the strategy is represented (Logan, 1980a; Logan & Zbrodoff, 1979). The different results with different responses to the probes point out important limitations on previous studies of probe interference and of cost-benefit analysis, which each focused on a single dimension of cost and benefit. The differences suggest that a multiple-resources approach to probe interference and cost-benefit analysis might be more appropriate.     

Analogical reasoning in 2-year-olds: The development of access and relational inference

Eighty-four 24- and 30-month-old children were tested with two analogy tasks: formal and problem solving. Experiment 1 included three Groups: relations specified, relations unspecified, and associative control (no exposure to base relations). In Experiment 2 the relation that linked that a- and b-terms in formal problems was explicitly shown in order to reduce relational inference demands. In Experiment 1, children responded systematically to the formal problems when given two chances to answer each question. In Experiment 2, children were systematic on their first responses. In the problem-solving task the rates of spontaneous analogies produced were similar to those seen in older children. However, unlike older children, 2-year-olds benefited minimally from prompts. We believe this may indicate that 2-year-olds have difficulty explicitly controlling their analogical activity. We conclude early analogical abilities may be limited by weak relational inference abilities and difficulty intentionally initiating access.     

Dissociation between Categorical and Coordinate Spatial Computations: Modulation by Cerebral Hemispheres, Task Properties, Mode of Response, and Age

Kosslyn suggested a dissociation of two kinds of spatial representations: categorical and coordinate, the former computed by the left hemisphere and the latter by the right hemisphere. In addition, with practice, a “categorization” of the coordinate computation would appear. These suggestions resulted largely from an experiment, replicated by others, in which the subjects had to estimate the relative position of a dot and a line by giving an oral response, and feedback was provided. The present series of five experiments was an attempt to test whether this finding could be generalized, under several methodological manipulations, some of which have already been used by researchers in separate studies. In the five experiments, accuracy was a more contributive dependent variable than correct latencies, and practice effects on the task × field interaction were not verified. Experiments 1–3 concerned the kind of response. When a manual instead of an oral response was required (Experiment 1;n= 32 Ss), the expected dissociation was observed (as well as when the latency of responses made by the right hand were studied). When the number of oral responses was increased from two (a binary choice) to eight, the dissociation was still observed for accuracy but disappeared when a more liberal criterion of accuracy was used to reduce the considerable task effect (Experiment 2;n= 32 Ss), or when response requirements were equated for both tasks (Experiment 3;n= 32 Ss). In Experiment 4 (n= 32 Ss), a manual response was called but the feedback was removed and the task dissociation disappeared. Finally, the task dissociation observed in Experiment 1 was not verified when a sample of elderly subjects was enrolled (Experiment 5;n= 32 Ss). However, age per se was the source of an interesting additional dissociation since only the coordinate computation was age sensitive. Our results suggest that the dissociation proposed by Kosslyn between the computation of categorical vs coordinate spatial relationships is highly unstable and sensitive to subtle methodological factors (vocal vs manual response, presence vs absence of feedback, binary vs “continous” response, age) which could preclude its general application.