Effects of pattern orientation and number of symmetry axes on the detection of mirror symmetry in dot and solid patterns

It has been postulated that as the number of axes of symmetry in a pattern increases, so pattern 'goodness' increases. Recently, a distinction was made between two different theoretical accounts of regularity or 'goodness' in relation to patterns with mirror symmetry: the 'transformational' and the 'holographic' models. It was argued that the former predicts a 'goodness' ordering of four > three > two > one whereas the latter predicts four > two > three > one, where '>' means greater regularity or goodness. In three experiments, we have tested these predictions. In experiment 1, we measured percentage correct and reaction time to dot patterns which had one, two, three, or four axes of symmetry and were flashed for 150 ms. Experiment 2 was identical except that patterns were presented for 2000 ms. In experiment 3, dot patterns were replaced by solid shapes which also had one, two, three, or four axes of symmetry. Although it was found that stimuli with four axes clearly allowed superior performance to that of stimuli with one axis, results obtained with stimuli with two and three axes were almost identical and in between those obtained with one and four axes. The data thus support the suggestion that extra axes add 'goodness' to symmetrical patterns but not in a monotonic fashion.     

The abstraction and generalization of dot patterns

The Ss were trained on patterns representing different levels of distortion and transferred to test trials containing the old training patterns, the prototype patterns, and new distortions. Training on low levels of distortion consistently produced superior performance on all test patterns except the most distorted ones. The results also showed that the prototypes and low distortion-level test patterns of meaningful concepts were identified more often than prototypes and low distortion-level test patterns of meaningless concepts but the reverse was true for highly distorted test patterns. Training with patterns whose average dot positions corresponded to the original positions of the dots in the prototypes and to two different levels of distortion of training patterns did not facilitate transfer of any abstractions formed.     

Complexity and goodness of dot patterns varying in symmetry

Summary Two experiments were performed to specify stimulus determinants of pattern complexity and pattern goodness. Dot patterns distributed in 3×3 and 4×4 matrices with a rectilinear frame were used in Experiment 1, and dot patterns in hexagonal frameworks with a circular frame were used in Experiment 2. The patterns were invariant for transformations of rotation or reflection, and formed symmetry groups of different orders, i.e., cyclic and dihedral groups. The complexity and goodness of the patterns depended upon such stimulus variables as follows: (1) complexity decreased with the order of symmetry groups with equal weights for cyclic and dihedral groups, whereas goodness increased with the order of both symmetry groups with different weights; (2) the simplicity and goodness of patterns with a vertical axis were greater than those with a horizontal axis and those with an oblique one; (3) the complexity of the patterns that had collinear elements with equal length was rated the simplest; (4) pattern goodness increased as a function of the number of dots and the concentrations of dot to rotation/reflection axis in 3×3 and 4 × 4 matrices. Thus, complexity and goodness of pattern differed with respect to these stimulus variables.     

Anchor effects using numerical estimates of simple dot patterns

Shifts due to anchor stimuli using absolute judgments have been ascribed to “semantic” and “scale modulus” changes. To test this explanation, random dot patterns of 10, 12, 14, 16 and 18 dots were exposed for 0.30 sec with anchors of 4, 13 or 32 dots preceding each of the stimuli. In the control only the series of stimuli were judged. It was found that numerical estimates of the number of dots increased with small anchor, decreased with large anchor, and were not significantly changed with anchor in the vicinity of AL. These results exactly parallel those found using methods of absolute and comparative ratings and hence cannot be ascribed to semantic shifts especially in view of the fact that independent groups of Ss served in the four anchor and control conditions. Since the anchor effects were significant but not so large that they can be ascribed to change of scale modulus this theory must also be rejected. The AL model seems to offer the simplest and most unitary explanation of these as well as many other results obtained with different types of stimuli and different methods of judging.     

Iconic memory of dot patterns: preliminary report.

Pairs of complementary dot-pattern stimuli whereby each stimulus pair forms a bigram were used in an iconic memory paradigm. The variables of stimulus duration, interstimulus interval, dot density, and letter field were all shown to affect recognition performance of 15 naive college students.     

The relation between proximity and brightness similarity in dot patterns

The Gestalt studies demonstrated the tendency to visually organize dots on the basis of similarity, proximity, and global properties such as closure, good continuation, and symmetry. The particular organization imposed on a collection of dots is thus determined by many factors, some local, some global. We discuss computational reasons for expecting the initial stages of grouping to be achieved by processes with purely local support. In the case of dot patterns, the expectation is that neighboring dots are grouped as a function of proximity and similarity of contrast, by processes that are independent of the overall organization and the various global factors. We describe experiments that suggest a purely local relationship between proximity and brightness similarity in perceptual grouping.     

Lambda response by orientation of striped patterns.

A lambda response is an averaged occipital EEG potential associated with the offsets of saccadic eye movements. In the present experiment, two participants were asked to make horizontal saccades across horizontal or vertical white-black stripes. Analysis of orientations of striped patterns showed horizontal saccades across vertical stripes produced larger amplitudes of the lambda response than did horizontal saccades across horizontal stripes. Therefore, when the lambda response is used as the index of mental workload, it is necessary to take notice of the orientation of stimulus pattern.     

Parental identification and patterns of career orientation in college women

We argued that parental identification should be viewed as an intermediate variable which mediates the impact of parental characteristics on women's career orientation but does not directly affect career orientation itself. Questionnaire data from 457 college women showed that, while there was no overall association between career orientation and parental identification, these variables interacted significantly in their association with self-differentiation from the father, maternal employment and occupation, and maternal sex role ideology. As predicted, career orientation among mother-identified women was associated with more extensive maternal employment and less conventional sex role ideology in both parents. For this group it was also associated with greater dissimilarity between perception of self and father. For father-identified women, we hypothesized that career orientation would be associated with less dissimilarity between self and father, less extensive maternal employment, and greater maternal sex role traditionality. Results directionally supported this father-identified pattern.     

Discrimination of letters and random dot patterns by pigeons and humans

In a three-choice discrimination task, pigeons learned to distinguish each letter of the alphabet from all the other letters and each of 16 random dot patterns from all the others. Discrimination errors were used to generate a matrix of interletter and interpattern similarities. Human estimates of letter similarity were obtained from the literature, and human subjects rated the similarity of the dot patterns. Pigeon and human performances were described and compared through correlation, multidimensional scaling, and cluster analysis. Fits of the data by simple-feature and template models were computed and compared. The correlation between pigeon and human similarity matrices was .68 for letters and .72 for dot patterns. The other analyses revealed broadly similar patterns of results from the two species but suggested also that, relative to human data, the best fits to the pigeon data required fewer dimensions, fewer features, and fuzzier templates. There was some indication that pigeon discriminations depended on relatively simple features, and several of these were tentatively identified. The different methods employed might have influenced these apparent differences between pigeons and humans, but, overall, the results suggest considerable cross-task and cross species generality in the processing of these simple forms.     

Independent mechanisms for dividing attention between the motion and the color of dynamic random dot patterns

The present study investigated the division of attention between different visual attributes, which is a cognitive function implicated in the selection of information in a given condition. To examine the underlying mechanisms, we focused on motion and color as visual attributes. In Experiment 1, performance on single- and dual-judgment for motion and color of dynamic random dot patterns presented in a restricted visual field was examined under different priority conditions. Accuracy was the same for single- and dual-task conditions, and the attention operating characteristic (AOC) analysis indicated that motion and color perception do not share the same processing capacity. In addition, correlation analysis indicated that, on a trial-by-trial basis, performance on motion and color was considerably independent. In Experiment 2, a brief lateral cue preceded the dynamic random dot patterns. The cue affected only motion-judgment, even under dual-task conditions of motion and color. These results suggest that dividing attention between motion and color involves independent mechanisms.     

Detection of symmetry in tachistoscopically presented dot patterns: Effects of multiple axes and skewing

We examined the effects of multiple axes and skewing on the detectability of symmetry in tachistoscopically presented (100-msec) dot patterns to test the role of normal grouping processes based on higher order regularities in element positions. In addition to the first-order regularities of orientational uniformity and midpoint collinearity (Jenkins, 1983), bilateral symmetry (BS) gives rise to second-order relations between two pairs of symmetric elements (represented by correlation quadrangles). We suggest that they allow the regularity (i.e., BS) to emerge simply as a result of the position-based grouping that takes place normally, so that no special symmetry-detection mechanism has to be postulated. In combination with previously investigated variables— number and orientation of axes—we introduced skewing (resulting from orthographic projection of BS) to manipulate the kind and number of higher order regularities. In agreement with our predictions, the data show that the effect of skewing angle (varied at three 15° steps, clockwise and counterclockwise) on the preattentive detectability of symmetry (measured with d’) increases as the number of axes decreases. On the basis of some more specific findings, we suggest that it is not as much the number of correlation quadrangles that determines the saliency of a regularity as it is the degree to which they facilitate or “bootstrap” each other.     

Visual orientation by motion-produced blur patterns: Detection of divergence

Blur patterns are physiological “streaks” of photochemical and neural activity that occur whenever an observer and his visual environment are in relative motion. When retinal velocities are high, the impression of visual “flow” gives way to one of a field of “blur lines” whose patterns are rich with information about the motions and the optical textures that produced them. Simulated blur patterns were produced and thresholds measured for the detection of divergence at nine retinal loci. Sensitivity was somewhat greater in the central retina. Thresh-olds remained the same despite variations in pattern velocity, number of elements, and the presence or absence of an internal velocity gradient. Observers were able to orient above-threshold patterns, but consistently underestimated the amount of slant.