Biomedical subjects

Joachim Hoffmann

Publications and source records attributed to Joachim Hoffmann.

7 recordsLinked to original sources

PubMed2004

Anticipated action effects affect the selection, initiation, and execution of actions.

This study investigated the impact of contingent action effects on response production. In Experiment 1 responses of varying intensity were initiated faster when contingently followed by auditory effects of corresponding rather than of noncorresponding intensity. This response-effect (R-E) compatibility influence was robust with respect to practice, and it was not due to persisting influences of preceding R-E episodes. These results support the conclusion that R-E compatibility reflects the impact of anticipatory effect representations in response production. Experiment 2 showed that anticipatory effect codes have an impact on early processes of response production (response selection) as well as on processes that immediately precede overt responding (response initiation). Finally, they also influence the way the actions are physically performed (response execution). The results support and specify ideo-motor theories of action control that assume movements to be controlled by anticipations of their sensorial effects.

Adult↗

PubMed2003

The ideomotor principle and motor sequence acquisition: tone effects facilitate movement chunking.

Participants practiced short sequences of key presses; sequence length and response-effect mapping were the independent variables. Contingent, distinct key-effect relations were contrasted with either contingent but uniform or no response effects. In Experiment 1, tone effects were relevant as response-specific stimuli and also as effects. The sequence length effect for the tones group was reduced. In Experiment 2, participants were informed about the sequences to be executed and then given varying amounts of preparation time before the start signal. A reduction in the sequence length effect was observed, and initiation times and mean interresponse time (IRTs) were generally reduced in the tone group. Preparation time could compensate for some but not all of the latency reducing influence of the tone effects. The results are discussed with reference to ideomotor approaches to motor control, i.e., the notion that actions are represented in sensory format.

Adult↗

PubMed2003

Variable action effects: response control by context-specific effect anticipations.

The ideomotor principle (IMP) claims that bidirectional associations between actions and their contingent effects are acquired so that voluntary actions are accessed by the anticipation of intended effects. Until now, evidence for the IMP exists only for stable action-effect relations. The present paper explores whether the IMP also holds true for the initiation of actions for which no unconditional contingent action-effect relations exist. Participants responded with left and right key presses in two different contexts. They selected the responses according to the vertical (context A) or horizontal (context B) position of a target. Responses were followed by short/fast movements of the target in context A and comparatively long/slow movements in context B. Consequently, each response produced short and long effects equally often in both contexts. Nevertheless, RTs decreased in contexts with short effects and increased in contexts with long effects. Data confirm that action-effect associations were acquired context-specifically and that the same actions were accessed by different effect anticipations.

Adult↗

PubMed2003

Unique transitions between stimuli and responses in SRT tasks: evidence for the primacy of response predictions.

The present experiments aimed at separating the impact stimulus and response predictions have on serial learning and performance in SRT tasks. In Experiment 1, a unique transition between two of four responses in an otherwise random response sequence was triggered by ambiguous stimulus transitions, allowing local response predictions but no stimulus predictions. The data indicated explicit transition knowledge and strong performance benefits. In Experiments 2 and 3, unique transitions between two of four stimuli in otherwise random stimulus sequences allowed local stimulus predictions under conditions of ambiguous response transitions. The data indicated fragmentary explicit transition knowledge but no performance effects. Experiments 4a and 4b reveal that the inefficacy of the unique stimulus transitions in Experiments 2 and 3 was presumably due to the fact that the stimuli differed with respect to conjunctions of response relevant and response irrelevant features which participants did not have to attend. However, although in Experiments 4a and 4b unique transitions between response relevant stimuli were applied, substantial explicit transition knowledge but only marginal performance effects resulted. It is argued i) that in SRT tasks learning mechanisms are addressed that primarily strive for reliable predictions of forthcoming responses and ii) that for these mechanisms to work the predictors have to be attended. Response transitions are easily learned and used because both criteria are fulfilled. In contrast, pure stimulus transitions are learned only if the predictive stimuli are attended, and learned stimulus transitions become effective only to the extent that the predicted stimuli specify the required responses.

Adult↗

PubMed2003

Conscious control over the content of unconscious cognition.

Visual stimuli (primes) presented too briefly to be consciously identified can nevertheless affect responses to subsequent stimuli - an instance of unconscious cognition. There is a lively debate as to whether such priming effects originate from unconscious semantic processing of the primes or from reactivation of learned motor responses that conscious stimuli afford during preceding practice. In four experiments we demonstrate that unconscious stimuli owe their impact neither to automatic semantic categorization nor to memory traces of preceding stimulus-response episodes, but to their match with pre-specified cognitive action-trigger conditions. The intentional creation of such triggers allows actors to control the way unconscious stimuli bias their behaviour.

Adolescent↗

PubMed2003

The influence of response--effect compatibility in a serial reaction time task.

Participants performed a serial reaction time task, responding to either asterisks presented at varying screen locations or centrally presented letters. Stimulus presentation followed a fixed second-order conditional sequence. Each keypress in the experimental groups produced a contingent, key-specific tone effect. The critical variation concerned the mapping of tones to keys. In Experiment 1, keypresses in one control condition produced noncontingent tone effects, while in another control condition there were no tone effects. In Experiment 2, three different keytone mappings were compared to a control condition without tone effects. The results show that tone effects improve serial learning when they are mapped to the response keys contingently and in a highly compatible manner. The results are discussed with reference to an ideomotor mechanism of motor sequence acquisition.

Adult↗

PubMed2002

The impact of anticipated action effects on action planning.

Three experiments with a total of 72 participants investigated the assumption that motor actions are planned in terms of their sensorial effects. Participants had to prepare a certain action A that consistently led to a sensorial effect (a tone of certain pitch). Instead of (in Experiment 1) or before (in Experiments 2 and 3) the execution of the prepared action, another response B had to be carried out, which either resulted in the same or in a different auditory effect (a tone of same or different pitch). It was found that a to-be-executed response B was in general initiated more quickly when it resulted in the same effect as a concurrently prepared response A. The results are considered as evidence for the basic notion that the preparation and initiation even of very simple actions is mediated by an anticipation of their reafferences.

Adolescent↗