Mental imagery and the third dimension

What sort of medium underlies imagery for three-dimensional scenes? In the present investigation, the time subjects took to scan between objects in a mental image was used to infer the sorts of geometric information that images preserve. Subjects studied an open box in which five objects were suspended, and learned to imagine this display with their eyes closed. In the first experiment, subjects scanned by tracking an imaginary point moving in a straight line between the imagined objects. Scanning times increased linearly with increasing distance between objects in three dimensions. Therefore metric 3-D information must be preserved in images, and images cannot simply be 2-D "snapshots." In a second experiment, subjects scanned across the image by "sighting" objects through an imaginary rifle sight. Here scanning times were found to increase linearly with the two-dimensional separations between objects as they appeared from the original viewing angle. Therefore metric 2-D distance information in the original perspective view must be preserved in images, and images cannot simply be 3-D "scale-models" that are assessed from any and all directions at once. In a third experiment, subjects mentally rotated the display 90 degrees and scanned between objects as they appeared in this new perspective view by tracking an imaginary rifle signt, as before. Scanning times increased linearly with the two-dimensional separations between objects as they would appear from the new relative viewing perspective. Therefore images can display metric 2-D distance information in a perspective view never actually experiences, so mental images cannot simply be "snapshot plus scale model" pairs. These results can be explained by a model in which the three-dimensional structure of objects is encoded in long-term memory in 3-D object-centered coordinate systems. When these objects are imagined, this information is then mapped onto a single 2-D "surface display" in which the perspective properties specific to a given viewing angle can be depicted. In a set of perceptual control experiments, subjects scanned a visible display by (a) simply moving their eyes from one object to another, (b) sweeping an imaginary rifle sight over the display, or (c) tracking an imaginary point moving from one object to another. Eye-movement times varied linearly with 2-D interobject distance, as did time to scan with an imaginary rifle sight; time to tract a point varied independently with the 3-D and 2-D interobject distances. These results are compared with the analogous image scanning results to argue that imagery and perception share some representational structures but that mental image scanning is a process distinct from eye movements or eye-movement commands.     

Locational representation in imagery: The third dimension

Six experiments were conducted to test the relative processing characteristics of picture-plane and three-dimensional imagery as indexed by tasks that required subjects to keep track of successive locations in multiunit visual displays. Subjects were shown symmetrical displays either drawn on cardboard or constructed with three-dimensional blocks. They then were required to imagine these matrices and follow pathways through a series of adjacent squares (blocks) within the matrices. The pathways were described by a series of verbal terms that indicated the direction of the next square (block) in the pathway. Subjects experienced difficulty in performing the task with picture-plane displays composed of as few as 16 squares (4×4), but they rarely made errors with a three-dimensional matrix of 27 blocks (3×3×3). Performance with the three-dimensional task dropped dramatically when the matrix size was increased to 4×4×4. The results replicated previous findings that the image processing capacity for location in two-dimensional imagery is about three units in each direction, and they indicate that adding the depth dimension increases the capacity for representation of spatial location in imagery.     

Representationalism and the phenomenology of mental imagery

This paper sketches a phenomenological analysis of visual mental imagery and uses it to criticize representationalism and the internalist-versus-externalist framework for understanding consciousness. Contrary to internalist views of mental imagery imagery experience is not the experience of a phenomenal mental picture inspected by the mind’s eye, but rather the mental simulation of perceptual experience. Furthermore, there are experiential differences in perceiving and imagining that are not differences in the properties represented by these experiences. Therefore, externalist representationalism, which maintains that the properties of experience are the external properties represented by experience, is an inadequate account of conscious experience.     

Spontaneous imagery scanning in mental extrapolation

We report an experiment that suggests a functional application of mental-image scanning. After subjects inspected a simple dot pattern, the pattern was removed, and they were then shown an arrow at an unexpected location. Their task was to judge as quickly as possible whether the arrow pointed at any of the dots in the previously observed pattern. Although the subjects were never instructed to form or scan mental images, most of them reported having done so in order to make their judgments, and their reaction times were directly proportional to the distances separating the dots and the arrows, as typically found in image-scanning experiments. Imagery scanning may therefore serve a useful function when one must judge spatial relations between the positions of remembered objects and newly specified locations.     

Individual differences in spatial mental imagery

In this article, we report a new image-scanning paradigm that allowed us to measure objectively individual differences in spatial mental imagery—specifically, imagery for location. Participants were asked to determine whether an arrow was pointing at a dot using a visual mental image of an array of dots. The degree of precision required to discriminate “yes” from “no” trials was varied. In Experiment 1, the time to scan increasing distances, as well as the number of errors, increased when greater precision was required to make a judgement. The results in Experiment 2 replicated those results while controlling for possible biases. When greater precision is required, the accuracy of the spatial image becomes increasingly important—and hence the effect of precision in the task reflects the accuracy of the image. In Experiment 3, this measure was shown to be related to scores on the Paper Folding test, on the Paper Form Board test, and on the visuospatial items on Raven's Advanced Progressive Matrices—but not to scores on questionnaires measuring object–based mental imagery. Thus, we provide evidence that classical standardized spatial tests rely on spatial mental imagery but not object mental imagery.     

Retrieval-induced forgetting and mental imagery

In the present article, we present four experiments in which we examined whether mental imagery can initiate retrieval-induced forgetting. Participants were presented with word pairs (Experiments 1, 2, and 3) or narratives (Experiment 4) and then engaged in selective mental imagery about half of the details from half of the categories. The results indicated that mental imagery can produce the same pattern of impairment as retrieval practice (Experiment 1) and postevent questioning (Experiment 4). Additionally, mental imagery-invoked, retrievalinduced forgetting was found for category cued recall (Experiments 1, 3, and 4) and cued recall (Experiment 2); it was found to dissipate across a 24-h delay, but only when there was no pre-delay test (Experiment 3). Such retrieval-induced forgetting was also found for imagining from the first-person and third-person perspectives (Experiment 4). From these findings, we suggest that the underlying retrieval processes behind mental imagery can initiate retrieval-induced forgetting. The findings are discussed in terms of inhibitory processes.     

视觉表象可视化——视觉表象研究的新途径

功能磁共振技术在表象研究中得到广泛应用是表象研究追求客观化精确性的必然趋势。本文介绍了功能磁共振多变量模式分析方法及其演变历程,探讨了借助该方法实现“视觉表象可视化”的理论依据与亟待解决的关键问题。分析指出“视觉表象可视化”将为表象研究提供全新的研究视角与方法途径。     

Temporal change: the third dimension of personality disorder

Until fairly recently, almost everyone who learned about, or carried out research into, personality disorders was taken in by the notion that personality disorder was a stable entity whose main characteristic was persistence, at least between the time of adolescence to middle age. We also suspected that those with these disorders, unless they received specific and necessarily powerful interventions, would remain continuously handicapped. Now it is clear that change in personality is possible, often rapidly so in some groups, and undergoes dynamic development from its genesis in childhood onward, and, though often achieving equilibrium, can never be said to be fixed in its manifestations. Longitudinal studies also show that personality abnormality identified early in life, whether temporary or longer-lasting, has a major influence on mental development and disorder generally, and, while it is impossible to say at present whether this influence is causal, it does suggest that early intervention could confer long-term benefits. An initiative such as that currently developed for early intervention in psychosis is at least as apt for personality disorder.     

Explorations of creative visual synthesis in mental imagery

The mental synthesis of visual patterns has been previously studied by instructing subjects to imagine assembling the component parts in specific ways. We report two experiments that show that subjects can often discover recognizable patterns in imagery when the component parts are randomly chosen and are provided without instructions for how they might be assembled. On each trial, the subjects were given a set of three parts, consisting of geometric forms, lines, or alphanumeric characters, and were instructed to close their eyes and imagine combining the parts to make some type of recognizable pattern. They were successful in doing so on about 40 % of the trials. Many of these mentally synthesized patterns were strikingly creative, and few of them could be predicted, either by the experimenter or by the subjects themselves, simply by knowing what the parts were. On the contrary, most of the subjects reported that they had performed the task by imagining various combinations of the parts until a recognizable pattern “emerged.” These findings show that visual discoveries in imagery can be reliably induced under appropriate laboratory conditions.     

Positive mental imagery and mental health amongst university students in Pakistan

Mental health problems amongst university students pose a major public health challenge, and this is particularly the case in Pakistan. Alongside broader societal and cultural pressures, cognitive factors likely also play a role in the development of and resilience to mental health problems and may provide a feasible target for interventions. The current study built on previous research in primarily European samples investigating the relationship between one cognitive factor, positive future-oriented mental imagery, and mental health, extending this to a sample of university students in Pakistan (N = 1838). In a cross-sectional design, higher vividness of positive future-oriented mental imagery was associated with lower levels of depressive symptoms and higher levels of positive mental health amongst participants completing questionnaire measures on paper (N = 1430) or online (N = 408). In the sample completing the measures on paper, these relationships remained statistically significant even when controlling for socio-demographic and mental health-related variables. The results provide a foundation for further investigating positive mental imagery as a potential mechanism of mental health and intervention target amongst university students in Pakistan.     

The vertical dimension of mental functioning

Summary A hierarchical, six-level model of human intelligence is described. The first four levels, which correspond to those found in Bernstein's theory of motor control, are concerned with palaeokinetic regulations (A), synergies (B), the spatial field (C), and object actions (D). The two levels of the higher symbolic coordinations embody conceptual structures (E) and metacognitive coordinations (F). The model is supported by experimental results from several subfields of cognitive research: e.g., different types of learning are specifically connected with the components of this hierarchical structure. Learning by the restructuring of existing knowledge proceeds by means of the metaprocedures of level F. The incremental accumulation of factual information is connected with the conceptual base of level E. Proceduralization of this knowledge results in the build-up of perceptual automatisms of skilled action (level D), as is often case in the formation of expert knowledge. Arguments for the hierarchical architecture of perception, attention, memory, understanding, thinking, and imagination are provided, and some parallels are drawn with the organization of emotional and motivational processes. It is argued that general, interdisciplinary questions on the nature and sources of mental functioning must be approached with a kind of pluralistic methodology. These questions cannot be answered in an equally general vein, because the localization of mental processes on the vertical dimension of cognitive architecture is to be taken into account.     

Eye movements during visual mental imagery

It has long been debated whether eye movements play a functional role in visual mental imagery. A recent paper by Laeng and Teodorescu presents new evidence that eye movements are stored as a spatial index that is used to arrange the component parts correctly when mental images are generated.     

Effect of mental imagery on realizing affordances

Using a reaction time experiment, we examined whether imagining a response would lead to an increase in the frequency of its execution. During a pre-test and a post-test, participants had to respond as quickly as possible with either their left or their right hand, as they preferred, to the illumination of one of 17 target positions arrayed in front of them in a semicircle. Between these two phases, participants performed a practice condition. Each of 40 right-handed participants was assigned to one of four groups that differed in their practice condition: One group made only dominant-hand responses to all target locations, two imagery groups imagined dominant hand responses to all target locations, and the last group received a no-practice, control task. One imagery group received instructions emphasizing that imagery has a strong effect; the second group received instructions suggesting that imagery was not effective. The results showed an increased incidence of the practised response for both imagery groups during the post-test. No effect was found for the physical performance group and the control group. The change in performance for the imagery groups was not accompanied by a change in reaction time. The results are discussed in terms of imagining the realization of action possibilities and from a neuropsychological point of view.     

A case study of mental imagery deficit

We describe a patient with a deficit in imagery ability, following a left posterior cerebral artery infarction and possible anoxic episode. This deficit was inferred from the patient's performance on several tasks, including one in which normal adults are known to rely on imagery and two that tested imagery nonverbally, allowing us to examine the possibility of a language-imagery disconnection. In addition, we queried the patient on some cognitive capacities related to visual imagery: dreaming, geographical knowledge, and introspection regarding visual and auditory imagery. Hypotheses concerning the critical lesion site and underlying cognitive mechanism of image generation deficits are discussed in relation to this and other recent cases of impaired imagery ability with intact recognition ability, and the relevance of this deficit to the "imagery debate" is discussed.     

Neuroimaging of mental imagery: An introduction

Adaptive mechanisms to protect cognitive performance under stressors through compensation in energy investment have previously received much research attention. However, stressors have also often been found to substantially reduce both performance and investment. The mechanisms underlying this dual negative effect are still unclear. This study tested the hypothesis that stressors can immediately hamper performance, which in turn reduces energy investment in later phases. In an experiment (N=103), we compared control and stressor conditions (noise or time pressure), investigating the effects of stressors on performance and information-sampling investment (as behavioural measure of energy investment) in two phases of a judgement task. The results showed an instant negative effect of stressors on performance and a delayed negative effect on information-sampling investment. Furthermore, impaired initial performance predicted the decline in investment over time. Finally, the effects of stressors on investment decline were partially mediated through initial performance level. The present findings contribute to theories aiming to explain the relationship between hampered performance and motivational losses.