Mental Spatial Transformation Research Articles

A general spatial transformation process? Assessing the neurophysiological evidence on the similarity of mental rotation and folding

Mental rotation and mental folding are established as archetypal mental spatial transformation tasks. Yet, it is uncertain as to whether these tasks rely on a general spatial transformation mechanism or on dedicated processes. We scrutinized benchmark mental spatial transformation findings for and against the concept of a shared mechanism in two EEG experiments, on mental rotation and folding respectively. We found the typical increase in reaction times with greater transformation difficulties for both tasks, however there was no relationship between participants’ reaction time slope for each task. Analyses of event-related potentials revealed a negative going component 400–800 ms post stimulus onset which distinguished transformation from baseline in both tasks, but only differed between difficulty levels for mental rotation. We found that this component originated from two parietal sources. A central parietal source displayed negativity in this time period distinguishing only transformation from baseline conditions in mental rotation and folding. Additionally, a left parietal source showed the same pattern for mental folding as the central source, but rotation yielded greater negativity for higher difficulties. Time-frequency analyses revealed desynchronisation in broadband alpha power throughout mental rotation and folding trials in both parietal sources, commensurate with a cognitive load being placed on transformation and visuospatial systems. We discuss a possible functional explanation for the results in line with a general spatial transformation process, for which we argue the evidence is stronger than for distinct rotation and folding mechanisms.

Learning 4-D Spatial Representations Through Perceptual Experience With Hypercubes

Imagine a day when humans can form mental representations of higher-dimensional space and objects. These higher-dimensional spatial representations may enable us to gain unique insights into scientific and cultural advancements. To augment human spatial cognition from three to four dimensions, we have developed an interactive 4-D visualization system for acquiring an understanding of 4-D space and objects. In this paper, we examine whether humans are capable of formulating 4-D spatial representations through perceptual experience in 4-D space with 4-D objects. Participants learn about 4-D space and hypercubes through an interactive system, and are then examined on a series of 4-D spatial ability tests. They demonstrate the ability to perform perspective taking, navigation, and mental spatial transformation tasks in 4-D space. The results provide empirical evidence that humans are capable of learning 4-D spatial representations. Moreover, the results support the interpretation that humans form a cognitive coordinate system, consisting of an origin and four directional axes, to understand 4-D space and objects.

Where music meets space: Children’s sensitivity to pitch intervals is related to their mental spatial transformation skills

Relations have been found among various continuous dimensions, including space and musical pitch. To probe the nature and development of space-pitch mappings, we tested 5- to 7-year-olds and adults (N=69), who heard pitch intervals and were asked to choose the corresponding spatial representation. Results showed that children and adults both mapped pitches continuously onto space, although effects were stronger in older than younger children. Additionally, children’s spatial and numerical skills were tested, showing a relation between children’s spatial and pitch-matching skills, and between their spatial and numerical skills. However, pitch and number were not related, suggesting spatial underpinnings for pitch and number.

Disentangling neural processes of egocentric and allocentric mental spatial transformations using whole-body photos of self and other

Mental imagery of one's body moving through space is important for imagining changing visuospatial perspectives, as well as for determining how we might appear to other people. Previous neuroimaging research has implicated the temporoparietal junction (TPJ) in this process. It is unclear, however, how neural activity in the TPJ relates to the rotation perspectives from which mental spatial transformation (MST) of one's own body can take place, i.e. from an egocentric or an allocentric perspective. It is also unclear whether TPJ involvement in MST is self-specific or whether the TPJ may also be involved in MST of other human bodies. The aim of the current study was to disentangle neural processes involved in egocentric versus allocentric MSTs of human bodies representing self and other. We measured functional brain activity of healthy participants while they performed egocentric and allocentric MSTs in relation to whole-body photographs of themselves and a same-sex stranger. Findings indicated higher blood oxygen level-dependent (BOLD) response in bilateral TPJ during egocentric versus allocentric MST. Moreover, BOLD response in the TPJ during egocentric MST correlated positively with self-report scores indicating how awkward participants felt while viewing whole-body photos of themselves. These findings considerably advance our understanding of TPJ involvement in MST and its interplay with self-awareness.

The vestibular system: a spatial reference for bodily self-consciousness.

Self-consciousness is the remarkable human experience of being a subject: the “I”. Self-consciousness is typically bound to a body, and particularly to the spatial dimensions of the body, as well as to its location and displacement in the gravitational field. Because the vestibular system encodes head position and movement in three-dimensional space, vestibular cortical processing likely contributes to spatial aspects of bodily self-consciousness. We review here recent data showing vestibular effects on first-person perspective (the feeling from where “I” experience the world) and self-location (the feeling where “I” am located in space). We compare these findings to data showing vestibular effects on mental spatial transformation, self-motion perception, and body representation showing vestibular contributions to various spatial representations of the body with respect to the external world. Finally, we discuss the role for four posterior brain regions that process vestibular and other multisensory signals to encode spatial aspects of bodily self-consciousness: temporoparietal junction, parietoinsular vestibular cortex, ventral intraparietal region, and medial superior temporal region. We propose that vestibular processing in these cortical regions is critical in linking multisensory signals from the body (personal and peripersonal space) with external (extrapersonal) space. Therefore, the vestibular system plays a critical role for neural representations of spatial aspects of bodily self-consciousness.

Mental spatial transformations of objects and bodies: Different developmental trajectories in children from 7 to 11 years of age.

Despite the large body of knowledge on adults suggesting that 2 basic types of mental spatial transformation--namely, object-based and egocentric perspective transformations--are dissociable and specialized for different situations, there is much less research investigating the developmental aspects of such spatial transformation systems. Here, an "own body transformation" paradigm and a letter transformation task were employed in a group of children ranging from 7 to 11 years of age to respectively investigate the development of egocentric perspective transformations and object-related transformations. A group of 30 young adults was also administered the 2 experimental tasks. Moreover, the Temperament and Character Inventory (Cloninger, Przybeck, Svrakic, & Wetzel, 1994) was also administered to children and adults with the goal of testing for possible influences of personality traits on imagined perspective transformation abilities. We found that egocentric perspective transformations develop later than object-based transformations--namely, from 8 rather than 7 years of age. We also found that high scores on temperament and character scales reflecting the acceptance of others (i.e., cooperativeness) were positively related to the ability to engage in imagined perspective transformations, especially when such ability first appears (i.e., at 8 years of age). These findings were held to support the view that the 2 mental spatial transformation systems are separated in that they follow 2 different developmental trajectories and are differentially influenced by personality traits in children.

Individual differences in mental rotation: what does gesture tell us?

Gestures are common when people convey spatial information, for example, when they give directions or describe motion in space. Here, we examine the gestures speakers produce when they explain how they solved mental rotation problems (Shepard and Meltzer in Science 171:701-703, 1971). We asked whether speakers gesture differently while describing their problems as a function of their spatial abilities. We found that low-spatial individuals (as assessed by a standard paper-and-pencil measure) gestured more to explain their solutions than high-spatial individuals. While this finding may seem surprising, finer-grained analyses showed that low-spatial participants used gestures more often than high-spatial participants to convey "static only" information but less often than high-spatial participants to convey dynamic information. Furthermore, the groups differed in the types of gestures used to convey static information: high-spatial individuals were more likely than low-spatial individuals to use gestures that captured the internal structure of the block forms. Our gesture findings thus suggest that encoding block structure may be as important as rotating the blocks in mental spatial transformation.

Separating mental transformations and spatial compatibility effects in the own body transformation task

Laterality judgments about the left or right hand of a schematic human figure, made from the perspective of the figure, are faster and more accurate when the figure is presented in back-facing view as compared to front-facing view. Mental perspective transformation accounts of this finding have recently been challenged on grounds of a confounding of facing direction with spatial stimulus-response (S-R) compatibility (Gardner and Potts in Acta Psychol 137: 371-381, 2011). We report two experiments that introduced stimulus figures in an orientation that was neutral in terms of spatial S-R compatibility. Results revealed a stable back-facing advantage that cannot be explained by compatibility conflicts. Comparisons of these neutral stimuli and conditions with figures presented in upright or upside-down orientation, however, confirmed a substantial impact of spatial S-R compatibility in the latter conditions. The present experiments show that it is possible to distinguish between mental transformation and incompatibility costs allowing future work to focus on the specialized mental spatial transformation processes.

Imagined paralysis impairs embodied spatial transformations

Recent studies showed that motor deficits and limb amputations selectively impair mental rotation of respective body parts. This is due to modifications in the body schema, which plays a pivotal role in bodily related mental spatial transformations. In the present study, we investigated whether imagined paralysis could affect mental transformations in healthy participants. Participants were required to make leg laterality judgments of imitable and non-imitable body postures that were presented at different orientations. Mental spatial transformation of imitable body posture relies on emulation processes, a mechanism through which the posture is covertly imitated by the observer. Imagined paralysis selectively impaired mental transformation of imitable body postures. These results reflect an inability to fully emulate stimulus postures, suggesting a modulation in the body schema. Our results show that the body schema incorporates top-down information about motoric constraints which can influence embodied cognition in healthy participants.

Early Education for Spatial Intelligence: Why, What, and How

Spatial representation and thinking have evolutionary importance for any mobile organism. In addition, they help reasoning in domains that are not obviously spatial, for example, through the use of graphs and diagrams. This article reviews the literature suggesting that mental spatial transformation abilities, while present in some precursory form in infants, toddlers, and preschool children, also undergo considerable development and show important individual differences, which are malleable. These findings provide the basis for thinking about how to promote spatial thinking in preschools, at home, and in children's play. Integrating spatial content into formal and informal instruction could not only improve spatial functioning in general but also reduce differences related to gender and socioeconomic status that may impede full participation in a technological society.

Egocentric and object-based transformations in the laterality judgement of human and animal faces and of non-corporeal objects

Mental rotation of body parts is influenced by specific sensory-motor information, and may be performed using an egocentric (subject-based) or an object-based mental transformation. Neurologically healthy volunteers were asked to verbally judge the laterality of visually presented human face, owl face and front of a car with a black patch over one eye/headlight, presented in one of eight orientations. Subjects may or may not have their head held in a head brace. The transformation used to solve the task was assessed with a questionnaire. Response times were non-monotonical at 180° for the object-based group, but not for the group using egocentric transformation. Having head movement constrained by the use of a head brace (“fixed”) or not (“moving”) did not influence performance. Within the two groups, no differences were found between the three types of stimuli. Hence, the response profile for mental rotation of human faces and face-like stimuli depended on the type of mental spatial transformation used to solve the task, independently from the possibility to move the head and from the kind of stimuli processed.

Time-resolved fMRI of mental rotation revisited-dissociating visual perception from mental rotation in female subjects

Functional neuroimaging studies have demonstrated that mental rotation paradigms activate a network of spatially distributed cortical areas rather than a discrete brain region. Although the neuro-anatomical nodes of the rotation network are well established, their specific functional role is less well identified. It was the aim of the present study to dissociate network components involved in the visual perception of 3D cubic objects from regions involved in their mental spatial transformation. This was achieved by desynchronizing the time course of the perceptional process (i.e., stimulus duration) from the duration of the cognitive process (i.e., reaction times) and by comparing these with the temporal characteristics of the hemodynamic response functions (HRFs) in regions of interest. To minimize intersubject variability, an all-female subject group was chosen for this investigation. Time-resolved fMRI analysis revealed a significant increase in the full width at half maximum (FWHM) of the HRF with reaction times in the supplementary motor area (pre-SMA), in the bilateral premotor cortex (PMd-proper), and in the left parietal lobe (PP). The FWHM in visual system components such as the bilateral lateral occipital complex (LOC) and dorsal extrastriate visual areas (DE) was constant across trials and roughly equal to the stimulus duration. These findings suggest that visual system activation during mental rotation reflects visual perception and can be dissociated from other network components whose response characteristics indicates an involvement in the mental spatial transformation itself.

Selective disturbance of mental rotation by cortical stimulation

In order to plan activity, people must imagine the spatial consequences of potential actions. Two classes of mental spatial transformation can be distinguished: Object-based spatial transformations are imagined movements of objects, such as mental rotation. Egocentric perspective transformations are imagined changes in one’s viewpoint, such as imagining one’s self in the position of another person. Here we report a case in which electrical stimulation of the right parietal cortex selectively interfered with performance of a mental rotation task. Interference was selective to this stimulation site, and was task specific. Performance of the perspective transformation task, and a control for visual encoding and responding, were unimpaired by stimulation. This marks the first instance of the use of direct cortical stimulation to investigate mental spatial transformations.

A Parametric Study of Mental Spatial Transformations of Bodies

Two classes of mental spatial transformation can be distinguished: Object-based spatial transformations are imagined movements of objects; and egocentric perspective transformations are imagined movements of one's point of view. The hypothesis that multiple neural systems contribute to these mental imagery operations was tested with functional MRI. Participants made spatial judgments about pictures of human bodies, and brain activity was analyzed as a function of the judgment required and the time taken to respond. Areas in right temporal, occipital and parietal cortex and the medial superior cerebellum appear to be differentially involved in object-based spatial transformations. Additionally, midline structures and lateral parietal cortex were found to decrease in activity during the spatial reasoning tasks, independently of the judgment required or of the latency of response. The results are discussed in terms of a model of spatial reasoning that postulates specialized subsystems for performing object-based and egocentric perspective image transformations.

Mental spatial transformations of objects and perspective

This study sought evidence for the independence of two classes of mental spatial transformation: object-based spatial transformations and egocentric perspective transformations. Two tasks were designed to selectively elicit these two transformations using the same materials, participants, and task parameters: one required same-different judgments about pairs of pictures, while the other required left-right judgments about single pictures. For pictures of human bodies, the two tasks showed strikingly different patterns of response time as a function of stimulus orientation. Moreover, across individuals, the two tasks had different relationships to psychometric tests of spatial ability. The chronometric and individual difference data converge with neuropsychological and neuroimaging data in suggesting that different mental spatial transformations are performed by dissociable neural systems.