Role of an Ideomotor Mechanism in Number Processing

The ideomotor principle predicts that the anticipation of expected sensory consequences precedes and controls voluntary goal-directed movements. Recent studies have revealed that an ideomotor mechanism could also support the link between finger movements and number processing. However, it is unknown whether such a mechanism is devoted to number processing per se, that is, without associated movement. In three experiments, we tested whether the ideomotor mechanism was also involved in a verbal number production task without associated goal-directed and motor dimensions. We tested this hypothesis in a response-effect (R-E) paradigm generally used to assess the ideomotor mechanisms. The results of Experiment 1 revealed a compatibility effect both in a stimulus-response task and an R-E task, suggesting the involvement of an ideomotor mechanism during number processing. More importantly, Experiment 2 revealed that performance in a motor imagery task correlated with the R-E compatibility effect, whereas performance in a visual imagery task did not, suggesting a distinct motor imagery contribution to R-E compatibility. Finally, Experiment 3 showed a strong R-E compatibility effect in a verbal word production task, but the correlations with motor or visual imagery tasks were not observed. Altogether, these findings suggest that ideomotor mechanisms play a specific and functional role in number processing.

Complexity of sensorimotor transformations alters hand perception

When using tools effects in body space and distant space often do not correspond or are even in conflict. The ideomotor principle holds that actors select, initiate and execute movements by activating the anticipatory codes of the movements’ sensory effects (Greenwald, 1970; James, 1890). These may be representations of body-related effects and/or representations of more distal effects. Previous studies have demonstrated that distant action effects dominate action control, while body-related effects are attenuated (e.g., Müsseler and Sutter, 2009). In two experiments, participants performed closed-loop controlled movements on a covered digitizer tablet to control a cursor on a monitor. Different gains perturbed the relation between hand and cursor amplitude, so that the hand amplitude varied and the cursor amplitude remained constant, and vice versa. Within a block the location of amplitude perturbation randomly varied (low predictability) or not (high predictability). In Experiment 1 both trajectories of hand and cursor followed the same linear path, in Experiment 2 a linear hand trajectory produced a curved cursor trajectory on the monitor. When participants were asked to evaluate their hand movement, they were extremely uncertain about their trajectories. Both, predictability of amplitude perturbation and shape of cursor trajectory modulated the awareness of one’s own hand movements. We will discuss whether the low awareness of proximal action effects originates from an insufficient quality of the humans’ tactile and proprioceptive system or from an insufficient spatial reconstruction of this information in memory.

Two Modes of Sensorimotor Integration in Intention-Based and Stimulus-Based Actions

Human actions may be driven endogenously (to produce desired environmental effects) or exogenously (to accommodate to environmental demands). There is a large body of evidence indicating that these two kinds of action are controlled by different neural substrates. However, only little is known about what happens—in functional terms—on these different “routes to action”. Ideomotor approaches claim that actions are selected with respect to their perceptual consequences. We report experiments that support the validity of the ideomotor principle and that, at the same time, show that it is subject to a far-reaching constraint: It holds for endogenously driven actions only! Our results suggest that the activity of the two “routes to action” is based on different types of learning: The activity of the system guiding stimulus-based actions is accompanied by stimulus–response (sensorimotor) learning, whereas the activity of the system controlling intention-based actions results in action–effect (ideomotor) learning.

Action generation and action perception in imitation: an instance of the ideomotor principle

We review a series of behavioural experiments on imitation in children and adults that test the predictions of a new theory of imitation. Most of the recent theories of imitation assume a direct visual–to–motor mapping between perceived and imitated movements. Based on our findings of systematic errors in imitation, the new theory of goal–directed imitation (GOADI) instead assumes that imitation is guided by cognitively specified goals. According to GOADI, the imitator does not imitate the observed movement as a whole, but rather decomposes it into its separate aspects. These aspects are hierarchically ordered, and the highest aspect becomes the imitator's main goal. Other aspects become sub–goals. In accordance with the ideomotor principle, the main goal activates the motor programme that is most strongly associated with the achievement of that goal. When executed, this motor programme sometimes matches, and sometimes does not, the model's movement. However, the main goal extracted from the model movement is almost always imitated correctly.