Right hemispheric specialization for mental imagery: A review of the evidence

An implicit assumption in the literature on functional hemispheric asymmetry is that the right hemisphere plays a special role in mental imagery. Using a definition of mental imagery as quasi-perceptual experience, we draw distinctions among visual imagery, visual recognition memory, and visuospatial abilities. We then review the research literature to evaluate the hypothesis that mental imagery is a specialized function of the right cerebral hemisphere, and find that it receives little unambiguous support. Case reports of loss of imagery are no more frequent with right than with left unilateral brain damage. Systematic studies of brain-injured patients provide some support for the hypothesis, but are also consistent with the alternative hypothesis of bilateral representation of imagery. Commissurotomized patients report dreaming and being able to form visual images. Behavioral and psychophysiological studies of non-brain-injured patients either fail to provide evidence in favor of the hypothesis or can be interpreted as compatible with the alternate hypothesis of bilateral hemispheric involvement in imagery. We conclude that there is, presently, insufficient empirical basis for considering imagery a right hemispheric function. We then discuss implications of this conclusion for future research.     

Cognitive processes in the solution of three-term series problems.

This study investigated the nature of strategies used in solving the three-term series problem. Three presentation modes (auditory, visual/sequential, and visual/simultaneous) were crossed with two question positions (before-premises and after-premises), for a total of six methods of problem presentation. Both high-spatial/imagal and low-spatial/imagal problems were employed, the assumption being that better performance on high-spatial/imagal problems reflected the use of a spatial/imagal strategy, while equal performance on both types of problems indicated the use of an alternative, perhaps verbal, strategy. It was hypothesized that different presentations would lead to differences in memory demands, input/processing interference, and mathemagenic behaviors, and thus to different problem-solving strategies. Response data and subjective reports confirmed this prediction. Results were discussed in terms of the Clark-Huttenlocher controversy (H. H. Clark, Linguistic processes in deductive reasoning, in Psychological Review, 1969, 76, 387--404; J. Huttenlocher, Constructing spatial images: A strategy in reasoning, Psychological Review, 1968, 75, 550--560).     

Solving deductive-reasoning problems after unilateral temporal lobectomy

The possible functional role of mental imagery in solving deductive-reasoning problems was investigated. Patients with left or right temporal lobectomies and normal control subjects had 32 different solvable three-term series problems read to them. Almost all subjects in the control and in the right-temporal-lobe groups reported consistent use of imagery in solving these problems, whereas less than half the left-temporal-lobe group reported using such a strategy. Overall, the left-temporal-lobe group was impaired relative to both the right-temporal and control groups. The right-temporal-lobe group was impaired only when the form of the question asked was not congruent with the form of the information in the premises. It was concluded that either (a) the left-temporal-lobe group had an unexpectedly large verbal comprehension deficit, or (b) the form of imagery utilized in solving deductive-reasoning problems is based upon verbal symbolic information, and as such is mediated by the left hemisphere.     

Highs Are to Lows as Experts Are to Novices: Individual Differences in the Representation and Solution of Standardized Figural Analogies

Two experiments compared the strategies used by high and lower scorers on standardized figural analogy tests to represent and solve problems. In Experiment 1, subjects freely sorted completed analogy (A:a::B:b) problems into categories. High scorers categorized problems largely on the basis of well-constrained spatial transformations between problem terms; Low scorers sorted according to perceptual (i.e., shape) similarities among the figures constituting the problems. Experiment 2 compared the two groups' solution strategies in terms of specific patterns of eye movements used in viewing problem and answer terms. High scorers appeared to view problem terms in a more efficient fashion than did lower scorers. The lower scorers focused on noncritical figural relations (mapping figure A onto figure B), and they devoted more resources to processing the answer alternatives than did the high scorers. The pattern of results supports the view that high scorers tend to work in a more forward, or constructive, fashion, whereas lower scorers more often work backwards, using a response-elimination approach. Taken together, these findings converge to suggest specific aptitude-related differences in the representation and solution of standardized figural analogy problems. These differences bear some similarities to expert-novice differences in a number of other problem-solving domains.     

视觉表象眼动的变化：知识还是技能表征的差异？

以表象看到一个运动员完成三级跳远项目为实验任务,对表象任务的信息通达水平、眼动注视点的活动位置和被试对三级跳远项目的知识水平和技能水平进行系统的操纵,通过2个实验探讨了视觉表象眼动的变化是基于知识学习表征差异还是技能训练表征差异的问题。实验1以没有三级跳远运动专业技能知识且对该运动的认知水平也较低的大学生为被试,结果表明,在完成高信息通达水平的表象任务时,注视点需要较短的持续时间,但眼跳距离会增大,眼跳频率会变低;实验2对表象任务的知识学习表征水平和技能训练表征水平进行操纵,分别以对实验任务进行过知识学习和专业技能训练的人为被试,结果表明,随着被试知识习得水平和技能水平表征能力的提高,不同表象任务信息通达水平间的眼动差异将消失,但知识学习和技能表征的差异在平均眼跳时间上有差异,技能训练型的被试其平均眼跳时间要短于知识学习型被试,达到临界水平显著,注视点平均持续时间和平均眼跳距离等均没有差异。     

从表征和认知过程上看表象与知觉、记忆的关系

表象、知觉和记忆是一个整合的认知系统。由于知觉和记忆提供了表象生成的材料,因而三者共享相似的表征,并激活广泛而相似的脑区。然而在认知加工过程上三者存在一定的差异。与知觉相比,表象的编码方式更抽象、更依赖过去经验的参与且处理细节能力更弱;与记忆相比,表象更容易受无关信息的干扰。未来对三者关系的研究应关注不同来源和不同类型的表象与知觉、记忆之间的关系,以及工作记忆在三者关系中所起的作用。     

Perception of nonlinguistic auditory rhythms by the speech hemisphere

Two groups of right-handed young adults were tested on a series of handedness measures and on dichotic nonverbal rhythmic sequences. Cross-validated multiple regression analysis revealed that all of the cerebral-lateralization/manual-praxis measures were positively related to the degree of left-hemisphere perceptual asymmetry for nonverbal rhythms (Crawford peg, scissor, handwriting, Crawford screws, tracing, total R = .67). Seventeen of the 52 subjects manifested significant (p < .05) left-hemisphere laterality coefficients for the dichotic stimuli. More complex rhythms elicited greater left-hemisphere perceptual preference. The results are discussed in reference to the concept of cerebral lateralization.     

What clocks tell us about the neural correlates of spatial imagery

We review a series of experimental studies aimed at answering some critical questions about the neural basis of spatial imagery. Our group used functional magnetic resonance imaging (fMRI) to explore the neural correlates of an online behaviourally controlled spatial imagery task without need for visual presentation—the mental clock task. Subjects are asked to imagine pairs of times that are presented acoustically and to judge at which of the two times the clock hands form the greater angle. The cortical activation elicited by this task was contrasted with that obtained during other visual, perceptual, verbal, and spatial imagery tasks in several block design studies. Moreover, our group performed an event‐related fMRI study on the clock task to investigate the representation of component cognitive processes in spatial imagery. The bulk of our findings demonstrates that cortical areas in the posterior parietal cortex (PPC), along the intraparietal sulcus, are robustly involved in spatial mental imagery and in other tasks requiring spatial transformations. PPC is bilaterally involved in different kinds of spatial judgement. Yet the degree to which right and left PPC are activated in different tasks is a function of task requirements. From event‐related fMRI data we obtained evidence that left and right PPC are activated asynchronously during the clock task and this could reflect their different functional role in subserving cognitive components of visuospatial imagery.     

Some properties of the visual imagery system investigated through backward spelling

Kosslyn (1973) and Kosslyn, Ball and Reiser (in press) have claimed that a quasi perceptual “scanning” process operates on visual images. Lea (1975) has suggested that this process should be redescribed in terms of iteration through an underlying list structure. It is known that images are subject to capacity limitations. This restriction of processing capacity suggests a model of imagery in which only information displayed in the image may be scanned, while iteration operates between such successive information displays. Three experiments on backward spelling from images support this view. Words of greater length involve more iteration problems. In Experiment I, backward spelling took longer than forward spelling for 8-letter but not for 4-letter words. Experiment II provides evidence for a directional scanning process, using a Brooksian interference technique. Experiment III demonstrates that the structure of the internal representation affects the manner in which it is iterated and that subjects can modify their iteration strategies.     

Tactile perception and the right hemisphere: A masculine superiority for imagery coding

Recent research regarding hemispheric lateralization has suggested complex interactions among observed asymmetries, subject coding strategies, and sex differences in the utilization of and access to information codes. Prior to tactile perception of ambiguous figures, subjects were instructed to use either a verbal (left hemisphere) or imagery (right hemisphere) strategy. A non-instruction control group was included. Although a significant overall relationship between instructed strategy and tactile asymmetries was observed, this largely was due to males' privileged access to right-hemisphere imagery codes.     

Putting in the mind versus putting on the green: expertise, performance time, and the linking of imagery and action

Does manipulating the time available to image executing a sensorimotor skill impact subsequent skill execution outcomes in a similar manner as manipulating execution time itself? Novice and skilled golfers performed a series of imaged golf putts followed by a series of actual golf putts under instructions that emphasized either speeded or nonspeeded imaging/putting execution. Novices putted less accurately (i.e., higher putting error score) following either putting or imagery instructions in which speed was stressed. Skilled golfers showed the opposite pattern. Although more time available to execute a skill enhances novice performance, this extra time harms the proceduralized skill of experts. Manipulating either actual execution time or imagined execution time produces this differential impact on novice and skilled performance outcomes. These results are discussed in terms of the functional equivalence between imagery and action and expertise differences in the attentional control structures governing complex sensorimotor skill execution.     

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.     

Imagery,propositions, and the form of internal representations

This paper has four major sections: First, we review the basic arguments offered by Pylyshyn (Psychological Bulletin, 1973, 80, 1–24) and others against using imagery as an explanatory construct in psychology. Second, we consider each of these points and find none that speak against any but the most primitive notions of imagery. Third, we review the results of various experiments on imagery. In each case, we compare two explanations of the findings: one which assumes the existence of a surface image manifesting emergent properties, and one which assumes that all internal representations are coded in terms of “abstract propositions.” We find imagery hypotheses to be at least as adequate as those based on propositional representation. Finally, we conclude that debate about the ultimate foundations of internal representation is fruitless; the empirical question is whether images have properties that cannot be derived directly from more abstract propositional structures.     

Latent inhibition: The effects of ITI and CS intensity during preexposure

Two experiments are reported which test the effects of intertrial interval (ITI) and stimulus intensity during nonreinforced preexposure in the latent inhibition paradigm. In Experiment 1, using mice in an escape-avoidance task, latent inhibition was a direct function of the duration of stimulus intertrial interval during preexposure. In Experiment 2, using rats in a CER task, latent inhibition was a direct function of stimulus intensity during preexposure. These findings are discussed in terms of equivalent effects which have been reported in the habituation paradigm.     

Impact of interpersonal problem-solving training on preschoolers' social competency

In order to test Shure and Spivack's theoretical position that a child's ability to verbally generate solutions to interpersonal problems and think about their consequences is directly related to the child's behavioral adjustment, preschoolers were tested on verbal problem-solving skills and their classroom behavior was rated by their teachers. Further, their behavior was observed by independent observers. No significant relationship between problem-solving skills and behavior was found. Following assessment, 54 of these children completed an 11-week training program, designed by Shure and Spivack, to improve their ability to think through and verbally generate solutions to interpersonal problems and to examine the possibility of mediation of such training to behavioral improvement. Preschoolers' ability to verbally generate alternative solutions to problems significantly increased due to training, however, this increase did not have an ameliorative effect on behavioral adjustment.     

Children's profiles of addition and subtraction understanding

The current research explored children's ability to recognize and explain different concepts both with and without reference to physical objects so as to provide insight into the development of children's addition and subtraction understanding. In Study 1, 72 7- to 9-year-olds judged and explained a puppet's activities involving three conceptual relations: (a) a+b=c, b+a=c; (b) a-b=c, a-c=b; and (c) a+b=c, c-b=a. In Study 2, the self-reports and problem-solving accuracy of 60 5- to 7-year-olds were recorded for three-term inverse problems (i.e., a+b-b=?), pairs of complementary addition and subtraction problems (i.e., a+b=c, c-b=?), and unrelated addition and subtraction problems (e.g., 3-2). Both studies highlighted individual differences in the concepts that children understand and the role of concrete referents in their understanding. These differences were related to using efficient procedures to solve unrelated addition and subtraction problems in Study 2. The results suggest that a key advance in children's conceptual understanding is incorporating subtractive relations into their mental representations of how parts are added to form a whole.     

文本表述和结构对小学生数学应用题表征的影响

以450名小学生为被试,探讨了文本表述和结构对小学生数学应用题表征成绩的影响。采用2(难度)×2(题材熟悉度)×5(措辞类型)×3(年级)四因素混合设计。结果表明:不同文本表述和结构对小学生解决数学应用题的影响不因年级的不同而不同;概念性措辞问题和情境性措辞问题都促进了小学生数学应用题的表征成绩;在容易问题中,额外信息对表征成绩影响较大;在较难问题中,数学运算关系难度对表征成绩影响较大;当解决文本背景较简单的标准措辞问题时,题材熟悉度对小学生的理解产生较大影响;文本长度对问题解决的影响取决于所增加的文本是否对理解问题的句法关系和语义情景有益。     

Free trees and bidirectional trees as representations of psychological distance

Two types of graph-theoretic representations of psychological distances or dissimilarities are proposed: weighted free trees and weighted bidirectional trees. A weighted free tree is a generalization of the sort of graph representation used in hierarchical clustering. A weighted bidirectional tree is a further generalization which allows for asymmetric dissimilarities. The properties of these structures are discussed and numerical methods are presented that can be used to derive a representation for any given set of dissimilarities. The applicability of these structures is illustrated by using them to represent the data from experiments on the similarities among animal terms and on memory for sentences. An analysis based upon free trees is compared and contrasted with analyses using hierarchical clustering and multidimensional scaling.     

Can Students Predict When Imagery Will Allow Them to Discover the Problem Solution?

Three studies have been carried out to identify to what extent and on what grounds undergraduates realise that visual imagery can be useful to solve a problem. A series of problems had been selected according to the kind of task (logical, mathematical, geometrical, and practical) and to the objective level of imagery efficacy (as reported by previous experiments aimed at assessing the effects of mental visualisation on problem solving). Then, by means of different procedures, students were asked to rate how useful, in their opinion, mental visualisation is in solving each of such problems and to explain why they thought it is useful. Results showed that usefulness scores were highly consistent and were not affected by gender, course of study attended, and individual differences in imagery (vividness, control, and cognitive style). Undergraduates rated imagery as useful above all when problems deal with concrete situations, whereas mental images were not perceived as possible aids for abstract or conceptual problems. The subjective evaluation did not correspond to the objective effect. However, when a specific imagery strategy was described, the discrepancy between the subjective and objective measures decreased.