Attenuation of alignment effect with exocentric encoding of location

An object's location is best retrieved from the orientation in which it was learned. Otherwise, retrieval necessitates a mental effort to restore the original perspective. In this case there is a cost to speed and accuracy of location responses known as the alignment effect. We hypothesised that one can attenuate this alignment effect by systematically referring objects in an exocentric frame of reference during learning. Sixteen male students were asked to learn the location of five objects disposed in a totally new environment either by locating the objects in an egocentric or in an exocentric spatial frame of reference. After the learning phase, the participants were asked to imagine orienting themselves to an object in the scene and to point to another object. The analysis of pointing accuracy, orientation, and pointing times showed that the performances of participants engaged in the exocentric condition remained insensitive to the augmentation of the angle between their actual position on the path and the imagined orientation. On the other hand, the participants engaged in egocentric learning were disoriented when the difference between their actual orientation and the imagined orientation was great. We conclude that when an object's location is intentionally referred to in an exocentric reference frame, alignment effect can be significantly reduced.     

For the mind’s eye the world is two-dimensional

The nature of visual mental images is a topic that has puzzled neuroscientists, psychologists, and philosophers alike. On the one hand, mental images might preserve the 3-D properties of our perceptual world. On the other hand, they might be akin to 2-D pictures, such as photographs, paintings, or drawings. In the present study, 16 observers judged where real objects (Experiment 1) or photographs thereof (Experiment 2) were pointing. Both experiments contained a perception condition and an imagery condition. In Experiment 1, there was a significant difference between the pointing errors in the perception and the imagery conditions, whereas there was no such difference in Experiment 2. In imagined objects, actual photographs, and imagined photographs, the direction in which the objects pointed followed the observer, regardless of his or her vantage point. The results from this study extend the rotation effect, typically found in pictures, to the domain of mental imagery. We found the rotation effect in pictures and mental images alike, but not in direct perception of 3-D objects; thus, we provide evidence that mental images share main characteristics of 2-D pictures.     

Some types of error in a choice response task

Errors from a serial response task involving single-finger responses to alphabetic stimuli are analysed and discussed in relation to findings which have been reported from tasks with more compatible stimulus-response relationships. Errors are divided into three distinguishable subsets and in each case found to have longer latencies than correct responses. Those which result from mirroring the required response about the centre of the hand are found to resist elimination during practice and their frequency seems to depend on the type of code used. In all cases error correction times are faster than the times to make a correct response but mirror errors and errors involving a finger adjacent to the correct response are corrected faster than other errors. The findings are discussed in relation to the theory of choice reaction time and error correction.     

Path completion after haptic exploration without vision: implications for haptic spatial representations

Subjects haptically explored two legs of a triangular path and responded by returning to the origin. Seven conditions were tested, varying in (1) whether the path was imaginally displaced between the initial exploration and the response; (2) the nature of the displacement, if present--rotation or translation; (3) variability in the origin location across trials; and (4) instructions to complete a triangle versus remembering the origin location. Mean distance and angle responses were modeled by the encoding-error model (Fujita, Klatzky, Loomis, & Golledge, 1993), which attributes errors to misencoding of the path legs and angle. The model failed to predict the finding of systematic errors in response distance but not response angle, a dissociation that held when the path was undisplaced or imaginally translated. Rotation before responding produced errors more consistent with the model. The data suggest use of a body-centered representation to complete undisplaced or imaginally translated paths, but adoption of an object-centered representation after imagined rotation, as is more consistent with pathway completion using whole-body locomotion.     

Action, verbal response and spatial reasoning

Studies have shown that perception of distance, orientation and size can be dissociated from action tasks. The action system seems to possess more veridical, unbiased information than the perceptual/verbal system. The current study examines the nature of the distinction between action and verbal responses in a spatial reasoning task. Participants imagined themselves facing different orientations and either pointed to where other objects would be, or verbally reported their egocentric directions (e.g., "50 degrees to my left"). When using pointing responses, RT and error increased as a function of the angular disparity between the imagined heading and their actual heading. However, when using verbal responses, performance was not affected by angular disparity, suggesting that participants knew the direction of the targets from the imagined perspective but could not point to them directly. The verbal and action systems have fundamentally different information or processes rather than quantitatively different ones.     

Egocentric updating of remote locations

The study examined whether people update remote spatial locations in unfamiliar environments during physical movement. Participants learned a layout of objects from one perspective and carried out perspective-taking trials after physically rotating to a new perspective in either the same room as learning or in an adjacent room. Prior to rotation in the adjacent room participants were instructed to visualize the objects as being around them. Responses to perspective-taking trials involved either pointing or verbal labeling. In both testing environments, participants pointed more efficiently from imagined perspectives aligned with either the initial learning perspective or their current facing orientation than from a novel imagined perspective; this indicates that they had updated the encoded spatial relations during the physical rotation and treated remote objects as immediate. Differences in performance among perspectives were less pronounced for verbal labeling in both environments, suggesting that this response mode is more flexibly used from imagined perspectives.     

The Distractor Picture Paradox in Speech Production: Evidence from the Word Translation Task

Several naming studies show that distractor pictures, even when intentionally ignored by the speaker, are still capable of activating their respective phonological representations. However results from word translation studies suggest that distractor pictures are only conceptually activated. Here we tested the reliability of the word translation results. In four experiments, bilingual participants translated words from one language to the other one while ignoring the presentation of pictures. In Experiment 1a phonological related pictures sped up translation latencies. However, the effect disappeared when the percentage of related trials was reduced (Experiment 1b). In Experiment 2a translation latencies were faster when the words were accompanied by semantically related pictures than by unrelated pictures. Importantly, the effect was still reliable when the proportion of related trials was reduced and the total number of semantic categories was increased (Experiment 2b). Theoretical implications of the influence of distractor pictures during speech production are discussed.     

Hand effects on mentally simulated reaching

Within the area of simulated (imagined) versus actual movement research, investigators have discovered that mentally simulated movements, like real actions, are controlled primarily by the hemispheres contralateral to the simulated limb. Furthermore, evidence points to a left-brain advantage for accuracy of simulated movements. With this information it could be suggested that, compared to left-handers, most right-handers would have an advantage. To test this hypothesis, strong right- and left-handers were compared on judgments of perceived reachability to visual targets lasting 150 ms in multiple locations of midline, right- and left-visual field (RVF/LVF). In reference to within group responses, we found no hemispheric or hand use advantage for right-handers. Although left-handers revealed no hemispheric advantage, there was a significant hand effect, favoring the non-dominant limb, most notably in LVF. This finding is explained in regard to a possible interference effect for left-handers, not shown for right-handers. Overall, left-handers displayed significantly more errors across hemispace. Therefore, it appears that when comparing hand groups, a left-hemisphere advantage favoring right-handers is plausible.     

Updating space during imagined self- and array translations

Previous work has demonstrated superior spatial updating performance during imagined viewer rotation versus imagined object/array rotation. Studies have also suggested that rotations are more difficult to process than translations. In three studies, we examined whether the advantage seen for updating during imagined self-rotations would generalize to translations. The participants updated the positions of objects in a line extending either to the front and back of the viewer or to the right and left after imagining viewer or array translation. Experiments 1 and 2 replicated the effects seen in imagined rotation tasks. A response time and accuracy advantage was found for imagined viewer translation versus imagined array translation. In Experiment 3, we directly compared real and imagined self- and array translations and demonstrated an advantage for real versus imagined array translation. The results suggest that the advantage for imagined viewer transformations is not a function of the specific transformation, but rather of the ability to imagine and predict the outcome of a moving frame of reference.     

Heart work after errors: Behavioral adjustment following error commission involves cardiac effort

Posterror slowing (PES) is the observation that people respond slower on trials subsequent to error commissions than on trials subsequent to correct responses. Different accounts have been proposed to explain PES. On the one hand, it has been suggested that PES arises from an adaptive increase in cognitive control following error commission, thereby making people more cautious after making an error. On the other hand, PES has been attributed to an orienting response, indicating that attention is shifted toward the error. In the present study we tested these accounts by investigating the effects of error commission in both flanker and switch tasks on two task-evoked cardiac measures: the interbeat interval—that is, the interval between two consecutive R peaks—and the RZ interval—that is, the interval between the R peak and the Z point—as measured using electro- and impedance cardiography, respectively. These measures allowed us to measure cardiac deceleration (autonomic orienting) and cardiac effort mobilization, respectively. Our results revealed a shorter RZ interval during posterror trials, indicating increased effort mobilization following errors. In addition, we replicated earlier studies that have shown cardiac slowing during error trials. However, multilevel analyses showed that only the posterror decrease in RZ interval predicted posterror reaction times, whereas there was no positive relationship between error-related cardiac deceleration and posterror reaction times. Our results suggest that PES is related to increased cardiac effort, supporting a cognitive-control account of PES.     

Effects of varied response modes upon dichotic consonant-vowel identification latency

Reaction times for two right-handed subjects who received 6000 trials of dichotic stop-vowels were obtained under response conditions involving the left hand, right hand, and neck muscles. Results indicated latencies were shorter (150+ msec) when targets were presented to the right rather than the left ear. Large and stable differences in latencies remained invariant with the mode of response. Reaction times did not vary as a function of the target's place or manner of articulation. The relationship between obtained measures of latency and percentage correct ruled out speed-accuracy trade-offs as a source of the obtained differences in latencies.     

Choice reaction times for temporal numerosity

Subjects watched rapidly presented visual sequences of two events until they decided which event was the more frequent. Accuracy was reduced both by increased rates of presentation and by the addition of more inconclusive information to the initial portion of the sequence. Response latencies were longest when there was no objective numerosity inbalance, and they decreased, for both correct responses and errors, when discrimination was relatively easy. The patterns of decision latencies for individual subjects could be represented on a continuum defined by the sensitivity of the latencies to the rate of event presentation and to the objective inbalance between the two events. The discussion points out formal and empirical similarities between sequential numerosity judgments and choice reaction times. The present results are discussed within the framework of a first-passage time model, to be developed formally in a subsequent paper.     

Use of cognitive versus perceptual heading during imagined locomotion depends on the response mode

Three experiments investigated whether the systematic errors previously observed in a triangle-completion task were caused by failures to form and update a cognitive heading or by use of perceived heading (even though an updated cognitive heading was available) during the response. These errors were replicated when participants indicated the origin of triangular paths they had imagined walking by turning their bodies toward the origin, but not when they responded verbally. The results indicate that participants are capable of updating their cognitive heading using imagined movements and suggest that the systematic errors previously observed were a result of the strong attachment of responses such as turns to a perceptual representation of the physical body.     

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.     

Effects of practice on the matching familiar figures test: A comparison of young,middle-aged and elderly adults

The purpose of the present study was to investigate the effects of practice on a modified version of the Matching Familiar Figures test in young, middle-aged and elderly adults. Forty-eight young, 48 middle-aged and 48 elderly adults were each presented with 48 match-to-standard items. the dependent variables were the number of errors committed and the latency to first response. the performance of both young and middle-aged adults reflected rather stable speed/accuracy trade-off decisions that did not change as a function of practice. the young adults responded more quickly and made more errors than the middle-aged adults across all 48 trials. the performance of elderly adults, on the other hand, did change as a result of practice; their latencies increased and their error rate decreased across trials. Elderly adults started out making more errors than young adults but by the end of the 48 trials, their error rate was lower than that of young adults. In the final trials, the error rate of elderly adults was midway between the rates of young and middle-aged adults. Thus, practice facilitated the performance of elderly adults but had no effect on the performance of young and middle-aged adults.     

对想象环境的空间更新

学界传统上将空间更新定义为个体随着身体运动对其所处真实环境空间表征的自动更新过程, 然而近年来有研究发现个体还可以对想象环境进行空间更新, 但其机制尚不明确。本研究实验1被试站在场景内学习物体空间位置之后, 保持学习朝向直线走到测试位置。其中, 0度组保持学习朝向站立, 180度组原地转动180度, 面对学习朝向的相反方向站立。两组被试均想象自己仍然站在学习位置, 面对学习朝向。然后被试旋转90度, 从3个想象朝向(记忆一致朝向、感觉运动一致朝向和不一致朝向)完成空间判断任务。结果发现0度组记忆一致朝向和感觉运动一致朝向成绩均优于不一致朝向, 而180度组无此优势。实验2被试从学习空间移动到测试空间过程中被迷向, 其他条件与实验1的180度组相同。但是, 实验2被试在记忆一致朝向和感觉运动一致朝向的成绩均优于不一致朝向。结果证明人们可以通过对在线空间表征进行想象平移或将离线记忆与空间更新系统相联结两种方式, 对想象环境进行空间更新。     

Passive tactile feedback facilitates mental rotation of handheld objects

Mental rotation of objects improves when passive tactile information for the rotating object accompanies the imagined rotation (Wraga, Creem, & Proffitt, 2000). We examined this phenomenon further using a within-subjects paradigm involving handheld objects. In Experiment 1, participants imagined rotating an unseen object placed on their upturned palms. The participants were faster at mental rotation when the object was rotated on their palm than when the object remained stationary. Experiment 2 tested whether the performance advantage would endure when the participants received tactile information for only the start- and endpoints of the rotation event. This manipulation did not improve performance, relative to a stationary control. Experiment 3 revealed that ambiguous tactile information, continuous with the rotation event but independent of object shape, actually degraded performance, relative to a stationary control. In Experiment 4, we found that continuous tactile rotation discrepant from imagined object movement also hindered performance, as compared with continuous tactile information aligned with imagined object movement. The findings suggest a tight coupling between tactile information specifying continuous object rotation and the corresponding internal representation of the rotating object.     

序列本体感觉学习获得稳定的自我中心空间表征*

通过同步视觉或者序列本体感觉,被试学习不规则场景。学习完毕之后,在面对学习方向、自主旋转240°、和持续旋转直至迷向3种运动条件下,被试随机指出各个物体的位置。迷向导致同步视觉学习组指向的内部一致性显著变差,而序列本体感觉学习组不受迷向影响。离线的相对位置判断任务表明两组被试的环境中心空间表征没有差异。这证明通过序列本体感觉学习被试也可以形成稳定的自我中心空间表征,支持了空间快照理论的扩展和空间认知的功能等价假说。     

Mental transformations in the identification of left and right hands.

Subjects determined as rapidly as possible whether each line drawing portrayed a left or a right hand when the drawings were presented in any of four versions (palm or back of either hand) and in any of six orientations in the picture plane. Reaction time varied systematically with orientation and, in the absence of advance information, was over 400 msec longer for the fingers-down orientation. However, when subjects were instructed to imagine a specified (palm or back) view of a specified (left or right) hand in a specified orientation, reaction times to test hands that were consistent with these instructions were short (about 500 msec), independent of orientation, and unacompanied by errors. It is proposed that subjects determine whether a visually presented hand is left or right by moving a mental "phantom" of one of their own hands into the portrayed position and by then comparing its imagined appearance against the appearance of the externally presented hand.     

Thinking ahead: the case for motor imagery in prospective judgements of prehension

How similar are judgements concerning how we expect to perform an action, to how we actually behave? The veracity of such prospective action judgements, and the mechanisms by which they are computed, was explored in a series of tasks that involved either grasping (MC conditions) or thinking about grasping (PJ conditions) a dowel presented in various orientations. PJs concerning limits of comfortable hand supination and pronation when turning a dowel in the picture plane were highly consistent with values obtained during actual hand rotation (Exp. 1). The same was true for judgements regarding the level of awkwardness involved in adopting a prescribed grip (e.g. overhand with right hand) for dowels in various picture plane orientations (Exp. 2). When allowed to select the most natural grip (overhand versus underhand) or hand (left versus right) for engaging dowels in these orientations, subjects preferred virtually identical responses in both PJ and MC conditions. In both instances, they consistently chose the least awkward response options. As would be expected for actual movements, PJs involving awkward hand postures had longer response times (RTs), and were less accurate. Likewise, latencies for both grip and hand judgements tended to increase as a function of the angular distance between the current positions of subjects' hands, and the orientation of the chosen posture. Together, these findings are consistent with a the hypothesis that PJs involve mentally simulated actions, or motor imagery. These results suggest that motor imagery does not depend on the existence of a completed premotor plan (Jeannerod, 1994), but may instead be involved in the planning process itself. A provisional model for the involvement of imagery in motor planning is outlined, as are a set of criteria for evaluating claims of the involvement of motor imagery in problem solving.