Instructed task demands and utilization of action effect anticipation.

Automatic acquisition of action effect associations may serve as a parsimonious account of how people acquire the basis for intentionally controlled action. However, recent research suggests that learning or the expression of action effect links might depend on whether task demands impose either a stimulus based mode of action control or an intention based action control mode. In the current study we develop a paradigm that allows the mode of action control to be varied via instructions while keeping stimuli identical. Participants were to respond to the location of a cloud of dots. Their actions were followed by predictable visual effects, either consistently congruent or incongruent with the location of the action. In Experiment 1, a displaced new cloud of random dots was presented as a spatial action effect. In Experiment 2 an arrow was presented as effect with a pointing direction congruent or incongruent to the response position. The location of the stimulus in the reference frame was easy to detect in some of the trials while the location of the cloud of dots was completely ambiguous in others. The instruction manipulation targeted the latter trials, suggesting to one group of participants to freely choose a key in a difficult trial, while asking another group to react to their spontaneous impression in the event of a difficult stimulus. In this way, we aimed at rendering actions either as stimulus driven or internally generated. By this we could investigate how effect anticipation changed with practice depending on action mode. We employed the impact of action effect compatibility on speed and choice of action as a measure for action effect anticipation. Our results suggest that action effect associations can be acquired when instructions suggest stimulus based action control or intention based action control. Instructions aiming at the mode of task processing can influence when and how action effect links influence behavior.

The activation of effect codes in response preparation: new evidence from an indirect priming paradigm.

Evidence for the anticipation of environmental effects as an integral part of response planning comes mainly from experiments in which the effects were physically presented. Thus, in these studies it cannot be excluded that effect codes were activated during response preparation only because the effects were displayed as external stimuli before response execution. In order to provide more clear-cut evidence for the anticipation of response effects in action planning, we performed a series of three experiments using a new paradigm, where displaying effect codes before the response was avoided. Participants first learned arbitrary effects of key-pressing responses. In the following test phase they were instructed to execute a response only if a Go stimulus was presented after a variable stimulus onset asynchrony (SOA). The Go stimulus was either compatible or incompatible with the effect, but independent of the response. In Experiment 1 we tested the paradigm with two responses and two effects. We found a significant compatibility effect: If the Go stimulus was compatible with the response effect, responses were initiated faster than in incompatible trials. In Experiment 2 response effects were only present in the acquisition phase, but not in the test phase. The compatibility effect disappeared, indicating that the results of Experiment 1 were indeed related to the anticipation of the forthcoming response effects. In Experiment 3 we extended this paradigm by using a larger number of stimuli and response alternatives. Again we found a robust compatibility effect, which can only be explained if the effect representations are active before response execution. The compatibility effects in Experiments 1 and 3 did not depend on the SOA. The fact that the Go stimulus affected response preparation at any time indicates that the role of effect anticipation is not limited to response selection.

The temporal dynamics of effect anticipation in course of action planning.

"Strong" versions of the ideomotor theory of action control claim that anticipations of the environmental effects that actions bring about are mandatory for response selection. This is considered to be the one and only way of how actions can be voluntarily selected. We studied this notion in a series of four experiments where we adapted the flanker paradigm to investigate the involvement of effect codes in the preparation of motor responses. Participants first learned that their responses to stimulus letters were contingently followed by the presentation of a new letter on the screen. In the second phase of the experiments, the action-demanding letters were presented together with the effects of the correct response, effects of other responses, or neutral letters. Varying the stimulus onset asynchrony (SOA) between target stimuli and the flanking effect stimuli provides the opportunity to investigate the temporal dynamics of the activation of effect codes. Hence, flanker stimuli were presented before, simultaneously with, or after the onset of the target. The results indicate that effect-related information from the flanker stimuli is involved in the preparation process, but mainly in later phases of response preparation. The observed pattern of results suggests that, at least under conditions where responses are determined by stimuli, effect codes are activated in course of response planning to enable the evaluation of the executed response and the monitoring of response execution, but they do not automatically activate the responses themselves.

Binding in voluntary action control.

The last decade has seen a proliferation of empirical studies that seek to understand how the cognitive system links voluntary motor actions with their perceptual effects. A view that has found considerable support in this research is the ideomotor approach to action control which holds that actors select, initiate, and execute a movement by activating anticipatory codes of the movement's sensory effects. We, first review the empirical evidence from different paradigms showing that effects of voluntary actions become anticipated during response production. In a second step we survey empirical data investigating the nature of the mechanisms that link voluntary motor actions with their intended and expected perceptual effects. We argue that the integration, or binding, of perceptual and motor codes occurs in action planning where features of intended effects are selectively bound to features of the actions that are selected to achieve these effects in the environment. As a final step we will summarize empirical findings that may elucidate the particular roles of effect-code activation in response production and control.

Strategic influences on implementing instructions for future actions.

Temporal and strategic factors that might influence the transformation of verbal task rules into functional stimulus-response associations were investigated in three experiments. In a dual task paradigm of the ABBA type participants were presented new S-R instructions for the A-task at the beginning of each trial. On varying proportions of trials No-go signals rendered the instructed A-task mappings irrelevant before instruction implementation was assessed during performance of an unrelated B-task. Our results indicate that participants refrain from implementing the mappings during instruction presentation when No-go signals appear frequently and late (Exp. 2), and that they can interrupt implementing instructed S-R mappings when frequent No-go signals appear early enough during implementation (Exp. 3). When No-go signals are rare and late, however (Exp. 1), the instructed stimulus features always activate their associated responses during performance of the embedded B-task in an automatic manner. Together, these findings suggest that participants strategically control whether or not they implement verbal instructions. Once implemented, however, instructed S-R associations influence behaviour even when the instructed mappings are no longer task relevant.

Instruction-induced feature binding.

In order to test whether or not instructions specifying the stimulus-response (S-R) mappings for a new task suffice to create bindings between specified stimulus and response features, we developed a dual task paradigm of the ABBA type in which participants saw new S-R instructions for the A-task in the beginning of each trial. Immediately after the A-task instructions, participants had to perform a logically independent B-task. The imperative stimulus for the A-task was presented after the B-task had been executed. The present data show that the instructed S-R mappings influence performance on the embedded B-task, even when they (1) have never been practiced, and (2) are irrelevant with respect to the B-task. These results imply that instructions can induce bindings between S- and R-features without prior execution of the task at hand.

The role of anticipation and intention in the learning of effects of self-performed actions.

The anticipative learning model for acquiring action-effect relations states that the acquisition of action-effect relations depends on processes that are part of action planning, in particular the anticipation of possible effects. Experiment 1 shows that response planning is indeed crucial for the learning of response effects. In this experiment distractors (tones) were presented either during response preparation or in the time interval between response execution and the presentation of a response effect. Response-effect learning was impaired when the distractors were presented during response preparation. The finding is consistent with the assumption that the distractors impaired the anticipation of potential effects and therefore reduced effect learning. In Experiment 2 all responses had two effects. Participants were instructed to produce one of the effects. Under this condition, response-effect learning was only found for the instructed effect, not for the non-instructed effect. The two experiments thus support the view that response-effect learning is selective and depends on the anticipation of potential effects during response planning. The results are discussed in terms of a model that explains both the learning of response-effect relations and the use of these effects for action control within the same theoretical framework.

Sequence learning in Parkinson's disease: the effect of spatial stimulus-response compatibility.

Patients with Parkinson's disease (PD) have repeatedly demonstrated reduced sequence-specific learning effects in serial reaction time tasks (SRTs). Previous research with PD patients has mainly employed the 'classical' SRT task, involving a spatially compatible assignment of stimuli and responses. From cognitive research, it is known that spatial compatibility triggers rapid, automatic responses in the direction of the stimulus. Automatic responding has shown to be disinhibited in PD patients and may therefore interfere with stimulus anticipation during the learning process. The aim of the present study was to test this hypothesis by investigating if reduced sequence-specific learning depends on spatial stimulus-response compatibility. PD patients and age-matched controls were examined either with an SRT variant involving central stimulus presentation, thereby preventing automatic linking of stimulus and response locations, or with a spatially compatible SRT task. Patients showed reduced sequence-specific learning effects only when the stimulus-response assignment was spatially compatible. This pattern of results confirms the hypothesis that sequence learning deficits in PD may result from a predominance of automatic response activation over learning-based stimulus anticipations during the learning phase.