A Gestalt account of human behavior is supported by evidence from switching between single and dual actions.

The question of how behavior is represented in the mind lies at the core of psychology as the science of mind and behavior. While a long-standing research tradition has established two opposing fundamental views of perceptual representation, Structuralism and Gestalt psychology, we test both accounts with respect to action representation: Are multiple actions (characterizing human behavior in general) represented as the sum of their component actions (Structuralist view) or holistically (Gestalt view)? Using a single-/dual-response switch paradigm, we analyzed switches between dual ([A + B]) and single ([A], [B]) responses across different effector systems and revealed comparable performance in partial repetitions and full switches of behavioral requirements (e.g.

Brain functional characterization of response-code conflict in dual-tasking and its modulation by age.

Crosstalk between conflicting response codes contributes to interference in dual-tasking, an effect exacerbated in advanced age. Here, we investigated (i) brain activity correlates of such response-code conflicts, (ii) activity modulations by individual dual-task performance and related cognitive abilities, (iii) task-modulated connectivity within the task network, and (iv) age-related differences in all these aspects. Young and older adults underwent fMRI while responding to the pitch of tones through spatially mapped speeded button presses with one or two hands concurrently.

Response modalities and the cognitive architecture underlying action control: Intra-modal trumps cross-modal action coordination.

Performing two actions at the same time usually hampers performance. Previous studies have demonstrated a strong impact of the particular effector systems on performance in multiple action control situations. However, an open question is whether performance is generally better or worse in situations in which two actions within the same effector system are coordinated (intra-modal actions: e.

Response-code conflict in dual-task interference and its modulation by age.

Difficulties in performing two tasks at once can arise from several sources and usually increase in advanced age. Tasks with concurrent bimodal (e.g.

Two sources of task prioritization: The interplay of effector-based and task order-based capacity allocation in the PRP paradigm.

When processing of two tasks overlaps, performance is known to suffer. In the well-established psychological refractory period (PRP) paradigm, tasks are triggered by two stimuli with a short temporal delay (stimulus onset asynchrony; SOA), thereby allowing control of the degree of task overlap. A decrease of the SOA reliably yields longer RTs of the task associated with the second stimulus (Task 2) while performance in the other task (Task 1) remains largely unaffected.

Effects of Input Modality on Vocal Effector Prioritization in Manual-Vocal Dual Tasks.

Doing two things at once (vs. one in isolation) usually yields performance costs. Such decrements are often distributed asymmetrically between the two actions involved, reflecting different processing priorities.

Motor sources of dual-task interference: Evidence for effector-based prioritization in dual-task control.

Dual tasking is known to yield performance costs. Corresponding research has often focused on early or central task processing stages, that is, on features related to stimulus processing or response selection. Here, we demonstrate the important role of the final (late) stage of task processing by studying effects of effector system combinations.

Free-choice saccades and their underlying determinants: Explorations of high-level voluntary oculomotor control.

Models of eye-movement control distinguish between different control levels, ranging from automatic (bottom-up, stimulus-driven selection) and automatized (based on well-learned routines) to voluntary (top-down, goal-driven selection, e.g., based on instructions).

Action scheduling in multitasking: A multi-phase framework of response-order control.

Temporal organization of human behavior is particularly important when several action requirements must be processed around the same time. A crucial challenge in such multitasking situations is to control the temporal response order. However, multitasking studies usually focus on temporal processing dynamics after a specific response order - which is usually triggered by stimulus sequence and instructions - has been determined, whereas a comprehensive study of response-order scheduling mechanisms is still lacking.

The rhythm of cognition - Effects of an auditory beat on oculomotor control in reading and sequential scanning.

Eye-movement behavior is inherently rhythmic. Even without cognitive input, the eyes never rest, as saccades are generated 3 to 4 times per second. Based on an embodied view of cognition, we asked whether mental processing in visual cognitive tasks is also rhythmic in nature by studying the effects of an external auditory beat (rhythmic background music) on saccade generation in exemplary cognitive tasks (reading and sequential scanning).

Backward crosstalk and the role of dimensional overlap within and between tasks.

In dual-task situations, which often involve some form of sequential task processing, features of Task 2 were shown to affect Task 1 performance, a phenomenon termed "backward crosstalk effect" (BCE). Most previous reports of BCEs are based on manipulations of code compatibility between tasks, while there is no clear picture whether and how mere Task 2 response selection difficulty (in the absence of cross-task dimensional code overlap, including effector system overlap) may also affect Task 1 performance. In the present study, we systematically manipulated response-response (R1-R2) relation (compatible, incompatible, arbitrary) and the stimulus-response (S-R) relation in Task 2 (S2-R2: compatible, incompatible, arbitrary; i.

Sources of interference in cross-modal action: response selection, crosstalk, and general dual-execution costs.

Performing several actions simultaneously usually yields interference, which is commonly explained by referring to theoretical concepts such as crosstalk and structural limitations associated with response selection. While most research focuses on dual-task scenarios (involving two independent tasks), we here study the role of response selection and crosstalk for the control of cross-modal response compounds (saccades and manual responses) triggered by a single stimulus. In two experiments, participants performed single responses and spatially compatible versus incompatible dual-response compounds (crosstalk manipulation) in conditions with or without response selection requirements (i.

Cross-modal Action Complexity: Action- and Rule-related Memory Retrieval in Dual-response Control.

Normally, we do not act within a single effector system only, but rather coordinate actions across several output modules (cross-modal action). Such cross-modal action demands can vary substantially with respect to their complexity in terms of the number of task-relevant response combinations and to-be-retrieved stimulus-response (S-R) mapping rules. In the present study, we study the impact of these two types of cross-modal action complexity on dual-response costs (i.