Implicit transfer of motor strategies in mental rotation

Recent research indicates that motor areas are activated in some types of mental rotation. Many of these studies have required participants to perform egocentric transformations of body parts or whole bodies; however, motor activation also has been found with nonbody objects when participants explicitly relate the objects to their hands. The current study used positron emission tomography (PET) to examine whether such egocentric motor strategies can be transferred implicitly from one type of mental rotation to another. Two groups of participants were tested. In the Hand-Object group, participants performed imaginal rotations of pictures of hands; following this, they then made similar judgments of pictures of Shepard-Metzler objects. The Object-Object group performed the rotation task for two sets of Shepard-Metzler objects only. When the second condition in each group (which always required rotating Shepard-Metzler objects) was compared, motor areas (Area 6 and M1) were found to be activated only in the Hand-Object group. These findings suggest that motor strategies can be covertly transferred to imaginal transformations of nonbody objects.     

The influence of spatial reference frames on imagined object- and viewer rotations.

The human visual system can represent an object's spatial structure with respect to multiple frames of reference. It can also utilize multiple reference frames to mentally transform such representations. Recent studies have shown that performance on some mental transformations is not equivalent: Imagined object rotations tend to be more difficult than imagined viewer rotations. We reviewed several related research domains to understand this discrepancy in terms of the different reference frames associated with each imagined movement. An examination of the mental rotation literature revealed that observers' difficulties in predicting an object's rotational outcome may stem from a general deficit with imagining the cohesive rotation of the object's intrinsic frame. Such judgments are thus more reliant on supplementary information provided by other frames, such as the environmental frame. In contrast, as assessed in motor imagery and other studies, imagined rotations of the viewer's relative frame are performed cohesively and are thus mostly immune to effects of other frames.     

When the brain simulates stopping: Neural activity recorded during real and imagined stop-signal tasks

It has been suggested that mental rehearsal activates brain areas similar to those activated by real performance. Although inhibition is a key function of human behavior, there are no previous reports of brain activity during imagined response cancellation. We analyzed event-related potentials (ERPs) and time–frequency data associated with motor execution and inhibition during real and imagined performance of a stop-signal task. The ERPs characteristic of stop trials—that is, the stop-N2 and stop-P3—were also observed during covert performance of the task. Imagined stop (IS) trials yielded smaller stop-N2 amplitudes than did successful stop (SS) and unsuccessful stop (US) trials, but midfrontal theta power similar to that in SS trials. The stop-P3 amplitude for IS was intermediate between those observed for SS and US. The results may be explained by the absence of error-processing and correction processes during imagined performance. For go trials, real execution was associated with higher mu and beta desynchronization over motor areas, which confirms previous reports of lower motor activation during imagined execution and also with larger P3b amplitudes, probably indicating increased top-down attention to the real task. The similar patterns of activity observed for imagined and real performance suggest that imagination tasks may be useful for training inhibitory processes. Nevertheless, brain activation was generally weaker during mental rehearsal, probably as a result of the reduced engagement of top-down mechanisms and limited error processing.     

On the relation between spontaneous perspective taking and other visuospatial processes

Common processes and representations engaged by visuospatial tasks were investigated by looking at four frequently used visuospatial research paradigms, the aim being to contribute to a better understanding of which specific processes are addressed in the different paradigms compared. In particular, the relation between spontaneous and instructed perspective taking, as well as mental rotation of body-part/non-body-part objects, was investigated. To this end, participants watched animations that have been shown to lead to spontaneous perspective taking. While they were watching these animations, participants were asked to explicitly adopt another perspective (Experiment 1), perform a mental object rotation task that involved a non-body-part object (Experiment 2), or perform a mental rotation of a body-part object (Experiment 3). Patterns of interference between the tasks, reflected in the reaction time patterns, showed that spontaneous and instructed perspective taking rely on similar representational elements to encode orientation. By contrast, no such overlap was found between spontaneous perspective taking and the rotation of non-body-part objects. Also, no overlap in orientation representation was evident with mental body-part rotations. Instead of an overlap in orientation representations, the results suggest that spontaneous perspective taking and the mental rotation of body parts rely on similar—presumably, motor—processes. These findings support the view that motor processes are involved in perspective taking and mental rotation of body parts.     

Domain general mechanisms account for imagined transformations of whole body perspective

Three experiments investigated the contribution of domain general processes to imagined transformations of whole body perspective. In a task where participants make left–right judgements about a schematic human figure, reaction times made from the point of view of the figure are longer when the figure does not share the same spatial orientation as the participant and are substantially longer than those made from the participant's own point of view. These phenomena have been attributed to a specialised mechanism for imagined perspective transformations. In the present experiments, the effect of orientation on performance was influenced by factors that affect spatial stimulus–response (S–R) compatibility; it was attenuated with reduced dimensional overlap and reversed by crossed S–R mappings. Performance in a control experiment in which no figure was present suggests that processes moderating S–R mappings may account for the effect of adopting another's point of view. Our findings demonstrate a role for domain general processes in imagined transformations of whole body perspective, imply that egocentric codes for spatial relationships within visually presented bodies are automatically generated, and undermine evidence for a specialised mechanism for imagined perspective transformations.     

Dissociating viewpoint costs in mental rotation and object recognition

In a mental rotation task, participants must determine whether two stimuli match when one undergoes a rotation in 3-D space relative to the other. The key evidence for mental rotation is the finding of a linear increase in response times as objects are rotated farther apart. This signature increase in response times is also found in recognition of rotated objects, which has led many theorists to postulate mental rotation as a key transformational procedure in object recognition. We compared mental rotation and object recognition in tasks that used the same stimuli and presentation conditions and found that, whereas mental rotation costs increased relatively linearly with rotation, object recognition costs increased only over small rotations. Taken in conjunction with a recent brain imaging study, this dissociation in behavioral performance suggests that object recognition is based on matching of image features rather than on 3-D mental transformations.     

The Influence of Motor Imagery on Postural Sway: Differential Effects of Type of Body Movement and Person Perspective

The present study examined the differential effects of kinesthetic imagery (first person perspective) and visual imagery (third person perspective) on postural sway during quiet standing. Based on an embodied cognition perspective, the authors predicted that kinesthetic imagery would lead to activations in movement-relevant motor systems to a greater degree than visual imagery. This prediction was tested among 30 participants who imagined various motor activities from different visual perspectives while standing on a strain gauge plate. The results showed that kinesthetic imagery of lower body movements, but not of upper body movements, had clear effects on postural parameters (sway path length and frequency contents of sway). Visual imagery, in contrast, had no reliable effects on postural activity. We also found that postural effects were not affected by the vividness of imagery. The results suggest that during kinesthetic motor imagery participants partially simulated (re-activated) the imagined movements, leading to unintentional postural adjustments. These findings are consistent with an embodied cognition perspective on motor imagery.     

Spatial updating in virtual reality: the sufficiency of visual information

Robust and effortless spatial orientation critically relies on "automatic and obligatory spatial updating", a largely automatized and reflex-like process that transforms our mental egocentric representation of the immediate surroundings during ego-motions. A rapid pointing paradigm was used to assess automatic/obligatory spatial updating after visually displayed upright rotations with or without concomitant physical rotations using a motion platform. Visual stimuli displaying a natural, subject-known scene proved sufficient for enabling automatic and obligatory spatial updating, irrespective of concurrent physical motions. This challenges the prevailing notion that visual cues alone are insufficient for enabling such spatial updating of rotations, and that vestibular/proprioceptive cues are both required and sufficient. Displaying optic flow devoid of landmarks during the motion and pointing phase was insufficient for enabling automatic spatial updating, but could not be entirely ignored either. Interestingly, additional physical motion cues hardly improved performance, and were insufficient for affording automatic spatial updating. The results are discussed in the context of the mental transformation hypothesis and the sensorimotor interference hypothesis, which associates difficulties in imagined perspective switches to interference between the sensorimotor and cognitive (to-be-imagined) perspective.     

Object-based and egocentric mental rotation performance in older adults: The importance of gender differences and motor ability

In this study, mental rotation performance was assessed in both an object-based task, human figures and letters as stimuli, and in an egocentric-based task, a human figure as a stimulus, in 60 older persons between 60 and 71 years old (30 women, 30 men). Additionally all participants completed three motor tests measuring balance and mobility. The results show that the reaction time was slower for letters than for both human figure tasks and the mental rotation speed was faster over all for egocentric mental rotation tasks. Gender differences were found in the accuracy measurement, favoring males, and were independent of stimulus type, kind of transformation, and angular disparity. Furthermore, a regression analysis showed that the accuracy rate for object-based transformations with body stimuli could be predicted by gender and balance ability. This study showed that the mental rotation performance in older adults depends on stimulus type, kind of transformation, and gender and that performance partially relates to motor ability.     

基于fNIRS的运动执行与运动想象脑激活模式比较

使用《运动想象问卷−修订版》筛选出的30名被试(男女各半), 采用功能性近红外光谱成像技术(fNIRS)监测被试在执行实际举哑铃(男生, 4磅和8磅; 女生, 2磅和4磅)任务和想象举同等重量哑铃任务时, 其大脑皮层氧合血红蛋白浓度的变化。结果发现：男女被试在运动执行与运动想象任务下都激活了主运动皮层; 且运动执行的大脑激活水平高于运动想象。在执行实际运动任务时, 运动强度显著影响大脑皮层血氧浓度的变化, 表现出左半球偏侧化优势; 在执行想象运动任务时, 运动强度没有影响大脑皮层血氧浓度的变化, 且无偏侧化现象。     

Stimulus size matters: do life-sized stimuli induce stronger embodiment effects in mental rotation?

Against the background of the embodied cognition approach this experiment investigated the influence of motor expertise on object-based vs. egocentric transformations in a chronometric mental rotation (MR) task using images of either the own or another person’s body as stimulus material. The present study aimed to clarify two issues: (1) whether stimulus size (life size vs. small) is able to induce embodiment effects and (2) which role self-awareness processes play when using stimuli of the own body. The same design was conducted twice using both small stimuli (Study 1) and life-size human figures (Study 2). Using life-sized figures in Study 2 resulted in an explicit advantage of self-related stimuli and improved performance for motor experts compared to non-motor experts in both object-based and egocentric transformations. In conclusion, these results suggest that life-sized figures do indeed induce stronger embodiment effects in MR.     

Mental rotation of objects retrieved from memory: a functional MRI study of spatial processing

This functional MRI study examined how people mentally rotate a 3-dimensional object (an alarm clock) that is retrieved from memory and rotated according to a sequence of auditory instructions. We manipulated the geometric properties of the rotation, such as having successive rotation steps around a single axis versus alternating between 2 axes. The latter condition produced much more activation in several areas. Also, the activation in several areas increased with the number of rotation steps. During successive rotations around a single axis, the activation was similar for rotations in the picture plane and rotations in depth. The parietal (but not extrastriate) activation was similar to mental rotation of a visually presented object. The findings indicate that a large-scale cortical network computes different types of spatial information by dynamically drawing on each of its components to a differential, situation-specific degree.     

Integrating cognitive psychology, neurology and neuroimaging

In the last decade, there has been a dramatic increase in research effectively integrating cognitive psychology, functional neuroimaging, and behavioral neurology. This new work is typically conducting basic research into aspects of the human mind and brain. The present review features as examples of such integrations two series of studies by the author and his colleagues. One series, employing object recognition, mental motor imagery, and mental rotation paradigms, clarifies the nature of a cognitive process, imagined spatial transformations used in shape recognition. Among other implications, it suggests that when recognizing a hand's handedness, imagining one's body movement depends on cerebrally lateralized sensory-motor structures and deciding upon handedness depends on exact match shape confirmation. The other series, using cutaneous, tactile, and auditory pitch discrimination paradigms, elucidates the function of a brain structure, the cerebellum. It suggests that the cerebellum has non-motor sensory support functions upon which optimally fine sensory discriminations depend. In addition, six key issues for this integrative approach are reviewed. These include arguments for the value and greater use of: rigorous quantitative meta-analyses of neuroimaging studies; stereotactic coordinate-based data, as opposed to surface landmark-based data; standardized vocabularies capturing the elementary component operations of cognitive and behavioral tasks; functional hypotheses about brain areas that are consistent with underlying microcircuitry; an awareness that not all brain areas implicated by neuroimaging or neurology are necessarily directly involved in the associated cognitive or behavioral task; and systematic approaches to integrations of this kind.     

Imaginal perspective switches in remembered environments: transformation versus interference accounts

Imaginal perspective switches are often considered to be difficult, because they call for additional cognitive transformations of object coordinates (transformation hypothesis). Recent research suggests that problems can also result from conflicts between incompatible sensorimotor and cognitive object location codes during response specification and selection (interference hypothesis). Three experiments tested contrasting predictions of both accounts. Volunteers had to point to unseen object locations after imagined self-rotations and self-translations. Results revealed larger pointing latencies and errors for rotations as compared to translations, and monotic latency and error increases for both tasks as a function of the disparity of object directions between real and imagined perspective. Provision of advance information about the to-be-imagined perspective left both effects unchanged. These results, together with those from a systematic error analysis, deliver clear support for an interference account of imaginal perspective switches in remembered surroundings.     

Motion in the mind’s eye: Comparing mental and visual rotation

Mental rotation is among the most widely studied visuospatial skills in humans. The processes involved in mental rotation have been described as analogous to seeing an object physically rotate. We used functional magnetic resonance imaging of the whole brain and localized motion-sensitive hV5/MT1 to compare brain activation for stimuli when they were mentally or visually rotated. The results provided clear evidence for activation in hV5/MT1 during both mental and visual rotation of figures, with increased activation for larger rotations. Combined with the overall similarities between mental and visual rotation in this study, these results suggest that mental rotation recruits many of the same neural substrates as observing motion.     

Conditional mechanisms of decision making

Decision making is an important link in the central part of a reflex—the “mental element” according to Sechenov. The reflex nature of this mental process is revealed in experiments where a voluntary motor reaction is chosen unconsciously as a response to subliminal conditional visual stimuli. Thus, learning which is reflected by “advance” or prior decision making can be performed unconsciously through a conditional reflex. But, once elaborated, temporary connections are preserved only in shortterm memory. They are not transferred to long-term memory, as in the case of recognition of signals. Decision making, being the central mental part of the reflex, like any activity of the brain, is performed in time by a certain cortical structure. Analysis of P₃₀₀ amplitudes shows that decision making is related to local activation of the frontal parts of the cerebral hemispheres. We suggest that the local activation of these areas is induced by conditional excitation of the neuronal mechanisms of focused attention. It provides a “command” to perform a voluntary motor reaction adequate to the conditions at hand. A large part of latency of voluntary motor response of man is spent on decision making, especially in discrimination of signals and in choice of reactions.     

Reconstruction from the mental image

In three experiments young children were asked to reconstruct an array of objects after they had imagined its appearance following either a rotation of the array or a change in their own position (Huttenlocher & Presson, 1973). In reconstructing arrays, subjects first positioned that object which would be most prominent to an observer following the imagined transformation. Surprisingly, this occurred even when subjects made an egocentric error by reconstructing a copy of the original array. Hence young children, although apparently egocentric, can imagine themselves in a new position with a new perspective. The mental operations which underlie imagined spatial transformations are discussed in light of the results.     

Comparing viewer and array mental rotations in different planes

Participants imagined rotating either themselves or an array of objects that surrounded them. Their task was to report on the egocentric position of an item in the array following the imagined rotation. The dependent measures were response latency and number of errors committed. Past research has shown that self-rotation is easier than array rotation. However, we found that imagined egocentric rotations were as difficult to imagine as rotations of the environment when people performed imagined rotations in the midsagittal or coronal plane. The advantages of imagined self-rotations are specific to mental rotations performed in the transverse plane.     

Bad things come easier to the mind but harder to the body: Evidence from brain oscillations

An intriguing finding of research on emotional processing is a discrepancy between perception and behavior. Perceptually, a robust finding is that negative stimuli are processed faster and more efficiently than positive stimuli. Behaviorally, a similarly robust finding is that response times are slower for negative than for positive stimuli. We proposed and tested a novel account to explain this still unexplained discrepancy, on the basis of the assumption that negative valence narrows perceptual processes to the benefit of speeded perception, but broadens motor processes at the cost of slowed responding. Participants performed a valence judgment task in which they responded with their left or right hand to negative and positive stimuli that were presented on the left or right, and we measured the activation of relevant/deactivation of irrelevant perceptual and motor processes, as revealed by the lateralization of electroencephalographic brain oscillations. Stimulus-related lateralization of alpha activity (8–12 Hz) over perceptual areas was increased for negative stimuli, indicating more efficient perceptual processing. By contrast, response-related lateralization of beta activity (20–25 Hz) over motor areas was decreased for negative stimuli, indicating less efficient response activation. Consistent with our predictions, more detailed analyses showed that both lateralization effects were caused by dynamics at the level of inhibiting irrelevant processes. For negative as compared to positive stimuli, the inhibition of irrelevant perceptual processes was increased, but the inhibition of irrelevant motor processes was decreased. These findings indicate that the discrepancy between perception and behavior in emotional processing may stem from asymmetrical effects of emotional valence on the breadth of cortical activations in perceptual and motor networks.     

Mental rotation and handedness: differences in object-based and egocentric transformations

This study investigates mental rotation performance of right- and left-handers in object-based and egocentric mental rotation tasks using human body stimuli with an outstretched arm in front and back view. Previous literature suggests that right-handers show a slightly better mental rotation performance than left-handers. 42 participants, 14 left-handers and 28 right-handers, completed a mental rotation task with object-based and egocentric transformation of a human figure which was displayed either in front or back view. The main result was a three-way interaction between the factors “kind of transformation”, “handedness” and “view” in a way, that right-handers show significantly faster reaction times then left-handers in front view object-based transformations because of the additional in-depth rotation for front view stimuli. This difference disappeared in egocentric tasks due to the modification of onés own perspective to solve the task. The results of this study show that right-handers not generally outperform left-handers in mental rotation tasks but only if more cognitive resources are needed.