Algorithms for processing spatial information

Pairs of stimuli taken from a psychometric measure of spatial aptitude were shown to 9-year-olds, 13-year-olds, and adults. The stimuli in pairs were (a) either identical or mirror images, and (b) presented in orientations that differed by 0-150 degrees. Individuals judged, as rapidly as possible, if the stimuli in a pair would be identical or mirror images if presented at the same orientation. In Experiment 1, in which the stimuli were letter-like characters, at all ages most persons solved the problems using an algorithm in which an individual encodes the stimuli in working memory, mentally rotates one stimulus to the orientation of the other, compares them to determine if they are identical, and responds. In Experiment 2, the stimuli were multielement flags; here, the modal algorithm for both 9- and 13-year-olds differed from the previously described algorithm in that if the comparison process revealed that the stimuli were dissimilar, individuals did not respond immediately, but continued processing until a self-imposed deadline was reached. Among adults, the modal algorithm was the same one used in Experiment 1. Results are discussed in terms of the roles of encoding in contributing to the use of a particular algorithm.     

Children's performance in mental rotation tasks: orientation-free features flatten the slope

Studies of the development of mental rotation have yielded conflicting results, apparently because different mental rotation tasks draw on different cognitive abilities. Children may compare two stimuli at different orientations without mental rotation if the stimuli contain orientation-free features. Two groups of children (78 6-year-olds and 92 8-year-olds) participated in an experiment investigating development of the ability to mentally rotate and the ability to recognize and use orientation-free features. Children compared two stimuli, one upright and one rotated, and responded as quickly as possible indicating whether the stimuli were the same or different. The stimuli were either two panda bears or two ice-cream cones with three scoops of ice-cream of different colors. The panda bears were either identical or mirror images. The cones were either identical, mirror images, or non-mirror images. Response times increased linearly as a function of the angle of orientation when stimuli were the same and when the stimuli were mirror images. But response times were much less dependent on angle of orientation for non-mirror image stimuli. Children as young as 6 years recognized orientation-free stimulus features and responded without mentally rotating when the task permitted this strategy.     

The impact of extended practice on rate of mental rotation

9-, 13-, and 20-year-olds were tested on 3840 trials of a mental rotation task in which they judged if pairs of stimuli presented in different orientations were identical or mirror images. Response time increased linearly as a function of the difference in orientation of the stimuli, and the slope of this function was used to estimate rate of mental rotation. At all ages, mental rotation became faster over trials. Age differences in rate of mental rotation were eliminated after approximately 1500 trials. At all ages the influence of practice was well characterized by hyperbolic and power functions. Furthermore, children's and adolescents' data were well fit by hyperbolic and power functions in which most of the parameters of those functions were constrained to adults' values. These results are discussed in terms of possible mechanisms underlying the impact of practice.     

Sex differences in mental rotation strategy

When humans decide whether two visual stimuli are identical or mirror images of each other and one of the stimuli is rotated with respect to the other, the time discrimination takes usually increases as a rectilinear function of the orientation disparity. On the average, males perform this mental rotation at a faster angular speed than females. This experiment required the rotation of both mirror-image-different and non-mirror-different stimuli. The polygonal stimuli were presented in either spatially unfiltered, high-pass or low-pass filtered versions. All stimulus conditions produced mental rotation-type effects but with graded curvilinear trends. Women rotated faster than men under all conditions, an infrequent outcome in mental rotation studies. Overall, women yielded more convexly curvilinear response functions than men. For both sexes the curvilinearity was more pronounced under the non-mirror-different, low-pass stimulus condition than under the mirror different, high-pass stimulus condition. The results are considered as supporting the occurrence of two different mental rotation strategies and as suggesting that the women were predisposed to use efficiently an analytic feature rotation strategy, while the men were predisposed to employ efficiently a holistic pattern rotation strategy. It is argued that the overall design of this experiment promoted the application of an analytic strategy and thus conferred an advantage to the female participants.     

Functional significance of stimulus orientation: effects on orientation discrimination.

Children (6- and 9-year-olds) and adults were required to discriminate identical pairs of visual stimuli from mirror images. It was hypothesized that a key factor in performance would be the extent to which orientation was a functionally significant attribute of the stimuli. Two variables were manipulated, type of orientation discrimination and stimulus class. The first variable refers to the fact that the mirror images could be produced by either left/right or top/bottom reversals. Three classes of stimuli, varying in the extent to which a particular orientation was emphasized, were used: mobile objects (for which left/right orientation is assumed to be important); stationary objects (which lack comparable relevance for left/right orientation); and novel, abstract forms. The prediction was that if the discrimination task involved left/right reversals, as contrasted with top/bottom reversals, subjects would show an advantage for mobile objects, producing an interaction between stimulus class and orientation discrimination. In the first study, the subjects were children and performance was measured in terms of error rates. In the second study adults were tested, and reaction times were measured. Both studies manifested the predicted interaction. Results are discussed in terms of an information-processing framework, in which the incorporation of orientation-related features in the code representing a stimulus varies with the functional significance of the orientation to the stimulus class.     

Development of mental rotation: A speed-accuracy study

Pairs of letters and numbers were shown to 11-, 14-, and 19-year-olds. One stimulus in a pair was presented upright. The second, which was either identical to the first or a mirror image of it, was rotated 0 to 150° from the vertical. Individuals judged if the stimuli in a pair would be identical or mirror images if presented at the same orientation. They did so under instructions that emphasized accurate responses, fast responses, or fast and accurate responses. Typically, responses were (1) most accurate and slowest when accuracy was emphasized, and (2) least accurate but fastest when speed was emphasized. The data from the three instructional conditions were used to derive measures of response times in which accuracy of response was equated for the three age groups. At 95% accuracy 14- and 19-year-olds mentally rotated stimuli at the same rate, which was faster than 11-year-olds' rate. At 100% accuracy, 19-year-olds mentally rotated stimuli more rapidly than both 11- and 14-year-olds, who did not differ from one another.     

Distinguishing clockwise from counterclockwise: Does it require mental rotation?

In three experiments, subjects were timed as they judged whether stimuli, presented in different angular orientations, represented clockwise or counterclockwise directions. In each experiment, there was also a control condition in which the subjects were required to make mirror image judgments relative to some canonical orientation. Analysis of reaction times suggested that, in the control tasks, the subjects generally rotated the stimuli mentally to the canonical orientation before making their decision. Mental rotation was invoked less frequently in the case of the experimental tasks, suggesting at least limited access to an orientation-free code representing the difference between clockwise and counterclockwise. This was most evident in Experiment 1, where the stimuli represented 1-h jumps of a hand on a clock face. It was less so in Experiment 2, where direction of motion was indicated in a static display. In Experiment 3, only a few subjects proved able to use an orientation-free, clockwise versus counterclockwise rubric in order to discriminate normal from backward letters.     

The locus of sex differences in spatial ability

College men and women judged whether pairs of stimuli were identical or mirror images. One stimulus of a pair was presented upright; the other was rotated 0°–150° from the vertical. The stimuli were either alphanumeric symbols or unfamiliar letter-like characters of the type found on the Primary Mental Abilities Spatial Relations Test. For each individual, the linear function relating response latency to degree of rotation was computed. The slope of this function was steeper for women than for men. Further, the distribution of slopes was more variable among women, with approximately 30% falling outside the range of distribution for men. Women and men were quite similar in the accuracy of their judgments, the intercepts of the latency functions, and the precision with which the linear function characterized the latency data. It is suggested that the sex difference in the slope of the rotation function may reflect differences in strategies of mental rotation.     

Impact of practice on speed of mental rotation

We tested 11- and 20-year-olds on 3360 trials of a mental rotation task in which they judged if stimuli presented in different orientations were letters or mirror images of letters. Children's and adults' processing times decreased substantially over practice. These changes were well characterized by hyperbolic and power functions in which most of the parameters of those functions were constrained to adults' values. Performance on two transfer tasks, mental rotation of letter-like characters and memory search for numbers, indicated that the practiced skill did not generalize to other domains. The results are discussed in terms of different mechanisms that might be responsible for the impact of practice.     

"Mirror-image" errors without mirror-image stimuli

Recent work has indicated that discrimination between upright and inverted stimuli is difficult when stimuli are one above the other, and discrimination between stimuli turned left and right is difficult when stimuli are side by side. That is, errors are frequent under conditions in which mirror-image confusions can be made. Young children were given a task requiring the matching of orientation of (a) identical realistic figures that could form mirror images of each other or (b) nonidentical realistic figures that could not form mirror images. The same pattern of errors appeared for the identical and nonidentical figures, indicating that the errors are not mirror-image confusions. It is argued that the errors are due to a strategy of matching analogous parts of the two figures.     

光栅朝向分辨学习中存在关于45°对角线对称的镜像迁

采用光栅朝向分辨任务来探讨视知觉学习中是否存在关于45°对角线对称的镜像迁移现象。训练被试分辨15°或75°朝向3或5天,每天约1小时,训练前后测量15°、75°、45°朝向的分辨阈值。通过训练,训练朝向（15°或75°）的阈值下降,该学习效应没有迁移至45°朝向,但基本迁移到关于45°对称的朝向（75°或15°）上。这提示,视知觉学习可能发生在中间视皮层,该皮层同时具有一定的朝向特异性和关于45°对角线对称的镜像迁移性     

Mental rotation and temporal contingencies.

A task that requires subjects to determine whether two forms of the same shape, but in different orientations, are mirror images or identical except for orientation is called a handedness recognition task. Subjects' reaction times (RT) on this task are consistently related to the angular disparity (termed alpha) between the two presented forms. This pattern of data has been interpreted to indicate that subjects solve the task by imagining that one of the forms rotates into the orientation of the other (termed mental rotation). The speed with which one imagines one of the forms rotating has been widely considered a fixed capability of the individual, and thus immune to the effect of contingencies. We present an experiment that assesses the effects of temporal contingencies in a handedness recognition task on the slope of the function RT = f(alpha). The data indicate that the slope of this function can come under the control of temporal contingencies.     

We've come a long way,maybe: College students' plans for work and family

Young men and women today face considerable choices as they plan for family and work. We explore college students' educational preparations, as well as their attitudes, orientations, and expectations for work and family. Although we find some changes toward a more gender-equal society, we also find potential conflicts which these individuals will have to face as they attempt to combine work and family roles. Women and men are doing equally well in college, both men and women have equal commitments to work roles, and both value family. However, both men and women expect that women will play a more prominent role in the family and men a stronger role in the workplace. The orientation and plans of these college students do not anticipate symmetrical relationships in which both men and women share household and work responsibilities.We are grateful to Brenda K. Hawks, Sue Curry Jansen, and Judith Lasker for their careful readings of earlier drafts of this paper. Special thanks go to the students in SR377/477 for their major contribution in collecting the data which are analyzed herein.     

Intratrial proactive interference in pigeon short-term memory: Manipulation of stimulus dimension and dimensional similarity

Proactive interference was studied using an intratrial preparation in two delayed matching-to-sample experiments employing pigeons. On interference trials, an interfering sample and a target sample were presented successively and were followed by a test consisting of a choice between two stimuli, one associated with each sample. Control trials were identical to interference trials except that the interfering sample was not presented. On both types of trials, choice of the comparison corresponding to the target sample was defined as correct. Colored fields and line orientations were employed as sample stimuli in Experiment 1, and samples of food and no food and of number of pecks were employed in Experiment 2. Interference was found to be equally robust regardless of whether the interfering and target samples were each selected from any of the four dimensions (color, line orientation, food/no food, or number of pecks). Amount of interference was found to be independent of whether the interfering and target samples employed on a trial were selected from the same dimension or from different dimensions. Evidence was also obtained suggesting that line orientation comparison stimuli are more likely to elicit a response not based on memory than are color comparison stimuli.     

The perception and identification of mirror-reversed patterns

Many species have difficulty in discriminating between mirror-image stimuli, especially those about a vertical axis, and when identificatory rather than purely perceptual processes are involved. Various theories are reviewed. In two experiments involving same-different judgments for pairs of stimuli, triangles or semicircles, these were simultaneously presented either unilaterally or bilaterally, and in mirror or aligned orientations with respect to each other. Mirror oriented stimuli presented to opposite cerebral hemispheres were no more readily matched than those possessing the same orientations (aligned), thus suggesting that at the perceptual level there is no interaction between mirror-corresponding points in the two visual cortices. Foreknowledge of stimulus orientations failed differentially to affect the findings. Two other studies were performed involving manual identification of single letters, correct or mirror oriented, in either visual field. Here, for most subjects, mirror reversal proved either less disruptive or even advantageous when in the visual field which is normally inferior with correctly oriented material. It was concluded that mirror-image confusion at the level of memory is almost certainly a consequence of reversed coding, in some form, in the opposite sides of the brain. A number of incidental findings were made with respect to visual field effects.     

Sea lions and equivalence: expanding classes by exclusion

Experiments have shown that human and nonhuman subjects are capable of performing new arbitrary stimulus-stimulus relations without error. When subjects that are experienced with matching-to-sample procedures are presented with a novel sample, a novel comparison, and a familiar comparison, most respond by correctly selecting the novel comparison in the presence of the new sample. This exclusion paradigm was expanded with two California sea lions that had previously formed two 10-member equivalence classes in a matching-to-sample procedure. Rather than being presented with a novel sample on a given trial, the sea lions were presented with a randomly selected familiar member of one class as the sample. One of the comparisons was a randomly selected familiar member of the alternative class, and the other was a novel stimulus. When required to choose which comparison matched the sample, the subjects reliably rejected the familiar comparison, and instead selected the unfamiliar one. Next, the sea lions were presented with transfer problems that could not be solved by exclusion; they immediately grouped the new stimuli into the appropriate classes. These findings show that exclusion procedures can rapidly generate new stimulus relations that can be used to expand stimulus classes.     

Winding one's ps and qs: mental rotation and mirror-image discrimination

Subjects were timed as they made judgments about ps and qs (also interpretable as ds and bs) in different angular orientations. Whether these judgments were left-right mirror-image discriminations (b vs. d or p vs. q) or up-down mirror-image discriminations (b vs. p or d vs. q), the subjects' reaction times increased sharply with the angular departure of each letter from its designated normal upright orientation, a fact implying mental rotation. This was so whether the subjects responded with the letter labels themselves (e.g., b vs. d) or with the labels left versus right or top versus bottom. It was again the case when the letters were replaced by nonletter forms, in which event there was also a left visual-field advantage in reaction time. This study is therefore the first to demonstrate a mental-rotation strategy when the canonical forms to be discriminated are up-down mirror images as well as when they are left-right mirror images. In both cases, however, the task requires the ability to tell left from right, and we suggest that this is the critical ingredient that induces mental rotation.     

Face processing in humans and new world monkeys: the influence of experiential and ecological factors

This study tests whether the face-processing system of humans and a nonhuman primate species share characteristics that would allow for early and quick processing of socially salient stimuli: a sensitivity toward conspecific faces, a sensitivity toward highly practiced face stimuli, and an ability to generalize changes in the face that do not suggest a new identity, such as a face differently oriented. The look rates by adult tamarins and humans toward conspecific and other primate faces were examined to determine if these characteristics are shared. A visual paired comparison (VPC) task presented subjects with either a human face, chimpanzee face, tamarin face, or an object as a sample, and then a pair containing the previous stimulus and a novel stimulus was presented. The stimuli were either presented all in an upright orientation, or all in an inverted orientation. The novel stimulus in the pair was either an orientation change of the same face/object or a new example of the same type of face/object, and the stimuli were shown either in an upright orientation or in an inverted orientation. Preference to novelty scores revealed that humans attended most to novel individual human faces, and this effect decreased significantly if the stimuli were inverted. Tamarins showed preferential looking toward novel orientations of previously seen tamarin faces in the upright orientation, but not in an inverted orientation. Similarly, their preference to look longer at novel tamarin and human faces within the pair was reduced significantly with inverted stimuli. The results confirmed prior findings in humans that novel human faces generate more attention in the upright than in the inverted orientation. The monkeys also attended more to faces of conspecifics, but showed an inversion effect to orientation change in tamarin faces and to identity changes in tamarin and human faces. The results indicate configural processing restricted to particular kinds of primate faces by a New World monkey species, with configural processing influenced by life experience (human faces and tamarin faces) and specialized to process orientation changes specific to conspecific faces.     

Mental rotation and perceptual uprightness

Performance in Cooper and Shepard’s (1973) mental rotation task was examined in the context of a model that defined the extent to which alphabet letters could be tilted from their normal orientation and still be perceptually upright. For letters with a broad range of orientations for which they remain perceptually upright, a nonlinear effect of orientation on reaction time was obtained (as in Cooper and Shepard). However, for letters with a narrow range of orientations for which they remain perceptually upright, reaction time was linearly related to orientation. The results supported the hypothesis that subjects in the Cooper and Shepard task would mentally rotate alphabet letters only when they were presented in orientations for which they were not perceptually upright.