Speed and accuracy in comparative judgments of line length

The paper presents an extension of Henmon’s (1906) finding that RT decreases as the difficulty of discriminating a difference between two line segments decreases. It is shown that, when an E RT deadline is imposed on the experimental task, RT remains constant with respect to changes in discrimination difficulty, but that correct response probability increases with increasing difference between two line segments. The data are examined in terms of current theories for the speed-accuracy trade-off.     

Similarity and preference judgments of musical stimuli

Two experiments were performed comparing similarity (technical-structural) and preference personal-affective) judgments of jazz improvizations (Experiment 1) and of classical, pop-rock, and jazz music (Experiment 2). A multidimensional scaling paradigm (INDSCAL) was used for pairwise comparisons of the 12 musical pieces in each experiment. Each 2 minute piece was subdivided into 10 second segments in order to reduce fatigue or boredom and provide better sampling across comparison trials. In general, similarity dimensions reflected greater agreement among the subjects that did preference dimensions and were hierarchically ordered. The dominant dimensions for both similarity and preference judgments of jazz improvizations were: Tempo, Dominant Instrument (Horns-guitar), and Articulation. The dominant dimensions for similarity judgments involving all three genres were: Classical-Contemporary, Jazz-Rock, and Tempo. The dominant dimensions for preference judments were: Rock-Classical, Jazz-Classical, and Tempo. In general, the preference judgments of musically sophisticated subjects were less constrained by salient dimensions.     

Similarity and attraction effects in episodic memory judgments

In the decision-making literature, it is known that preferences between two options can be influenced in different ways by the introduction of a third option. We investigated whether such influences could be demonstrated when making decisions about qualitative aspects of episodic memories. In a baseline condition, participants were asked which of two dissimilar events they remembered more vividly: (A) a well-known Olympic victory, or (B) the death of a well-known public figure. In two further conditions, a third event was added: (C) an Olympic victory similar and competitive to A, or (D) an Olympic victory similar but inferior to A. With the addition of C, participants were less likely to choose A than B (similarity effect), whereas with the addition of D, they were more likely to choose A than B (attraction effect), suggesting that effects known in decision-making can be generalised to relative judgments about episodic memories.     

Similarity, global matching, and judgments of frequency

In the test-pair similarity effect, forced-choice recognition is more accurate for similar test pairs, such as leopard-cheetah, than it is for unrelated test pairs, such as leopard-turnip. According to global matching models, this occurs because the retrieved familiarities of similar items are correlated. In the Minerva 2 model, global matching underlies frequency judgments as well as recognition memory. One implication of this model is that judged frequencies of similar items should be correlated. Another implication is that judgments of summed frequency for pairs of words (how many presentations were there of word1 and word2 combined?) should have higher variance when word1 and word2 are similar than when they are unrelated. These predictions were tested and confirmed in two experiments. A review of these and other results suggests that theories of recognition memory should also be applicable to frequency-judgment tasks.     

Similarity judgments and recognition memory for some common spices

A group of subjects rated the similarities of all 55 pairs of 11 spices, Nonmetric multidimensional scaling of this judgment matrix indicated a single underlying dimension, interpretable as pleasantness. Short-term recognition memory for the same spices was tested in separate groups of subjects required to remember one, three, and five stimuli, respectively. Performance was best for the group remembering one stimulus, but was not affected by the number of stimuli preceding the correct stimulus in the test. The confusion matrix for the one-stimulus group, symmetrized by removal of a stimulus bias, showed a significant correlation with the judgment matrix.     

The effects of angle-arm length on judgments of angle magnitude and orientation contrast

Acute angles frequently are overestimated, an effect that has been attributed to lateral inhibitory mechanisms. It can be derived from such theories that lengthening the arms of an angle should either reduce or not affect its judged subtense. However, in Experiments 1 and 2, it was found that angles with longer arms were judged larger. In Experiment 3, direct measures of anglearm orientation indicated that orientation contrast does not increase with angle-arm length, that it decreases with distance from the angle vertex, and that these effects are not averaged along the entire length of the arm. It follows that inhibitory mechanisms alone cannot explain why longer armed angles appear larger or why angle arms appear straight rather than bowed. It is suggested that a distinction is required between the orientation and the angular domains and that the latter judgments depend, at least partially, on the space or area within an angle. The fact that angles appear unbowed may reflect the fact that perceived orientation differences occur along an angle’s arm only when matches are made to small segments of the arm.     

Decision factors affecting line orientation judgments in the method of single stimuli

Just noticeable differences in orientation are smaller at principal standard orientations than at oblique standard orientations when they are measured with the method of single stimuli. We determined whether this oblique effect is due to an anisotropy in decision factors. A first series of experiments showed that the subjects compare the stimulus with an internal criterion, and that this decision rule is used at all standard orientations. A second series of experiments determined the influence on the oblique effect of nonsensorial variables related to criterion setting. The results strongly suggest that the effect is not due to a criterial noise anisotropy and that criterion-setting processes are similar at principal and oblique standard orientations. The latter conclusion was also supported by an analysis of the sequential stimulus and response dependencies in this task. Hence, it appears that the oblique effect in line orientation discrimination, when it is measured with the method of single stimuli, is due not to decision factors but to a sensorially based anisotropy.     

Voluntary visual attention and phenomenal line length

In 1956, Fraisse, et al. reported subjects judged that lines were longer when voluntary attention was focused on the lines than when attention was distracted from the lines. In the many attempts to repeat these results, none has ascertained whether attention on reported line length was a phenomenal effect. In the present study, 46 subjects were shown as stimuli pairs of horizontal or vertical briefly flashed lines with a fixation cross placed equidistant between the lines but far from each one. A change in color of one arm of the cross was used as a cue to focus subjects' voluntary attention on one line. Analysis showed attention increased the judged length of attended lines. Since this effect of attention also occurred when subjects were absolutely certain they saw the stimulus lines differed in length, this effect indicates that attention increased the phenomenal length of the attended lines. This lengthening was quite small: it involved a maximum mean increase of about .15 in the probability of the comparative response that the attended line was longer. This effect occurred in the horizontal dimension and was almost absent in the vertical dimension. In agreement with data indicating that flashed lines expand phenomenally by activating motion detectors and that focused attention makes neural motion responses increase in amplitude, the present results suggest that focused attention makes attended lines look longer because it makes these lines expand phenomenally more rapidly.     

Cross-modality matches of finger span and line length

Perceived finger span—the perceived spatial separation between the tip of the thumb and the tip of the index finger—was measured by using cross-modal matching to line length. In the first experiment, subjects adjusted finger span to match the length of line segments presented on a video monitor, and conversely, with both hands. Subjects also made estimates of finger span in physical units (“dead reckoning”). Finger spans were measured by using infrared LEDs mounted on the tip of the thumb and the finger tip, so the hand made no contact with any object during the experiment. Unlike in previous studies, the results suggest that perceived finger span is proportional to line length and slightly shorter than the actual span, provided that corrections are made for regression bias. The effect of finger contact was assessed in a second experiment by matching line length both to free span and to spans constrained by the pinching of blocks in the same session. The matching function when subjects were pinching blocks was accelerating, consistent with previous reports. In contrast, matched line length was a decelerating function of free span. The exponent of the free span matching function in the second experiment was slightly smaller than in the first experiment, probably due to uncorrected matching biases in the second experiment.     

Similarity judgments of same-category object representations: Effects of physical size,manipulability, and word frequency

ABSTRACT

Studies of object similarity have focused on the relationship between different physical objects and their mental representations or between instances of the same physical object and its mental representation. The present study is the first to investigate the structure of within-category psychological space. We provided evidence that large objects and frequently mentioned objects are perceived as less similar to each other compared to small objects or less frequently mentioned objects. Further, similarity judgments were higher for manipulable objects compared to non-manipulable objects. The relevance of these data to the isomorphism between physical and psychological spaces is also discussed.     

Nonmetric scaling of line lengths using latencies,similarity, and same-different judgments

An experiment investigating the relation between various ways of deriving psychophysical functions for line length is reported. A two-phase computer-controlled experiment in which the stimuli were pairs of lines was performed. In the first phase, the pair was presented for several seconds and the S was required to make a category judgment of the similarity of the lines. In the second phase, the pair was presented for a very brief period of time and the S decided whether the lines were the same or of different lengths. Three sets of data were analyzed: (1) the similarity judgments, (2) the proportion of correct different judgments, and (3) the latency of the correct different judgments. An individual differences analysis indicated that there were individual differences in the similarity and latency data. This analysis was not applicable to the proportion data. Nonmetric scaling revealed that the psychophysical functions based on all three sets of data were essentially identical     

The effects of tilted outline frames and Intersecting line patterns on judgments of vertical

The angular function of the rod-and-frame illusion has been attributed to the effects of the major, virtual axes of the frame. Only one of two possible interpretations of this hypothesis adequately accounted for vertical settings made in the presence of outline frames and intersecting line patterns tilted between vertical and 45 deg. The results obtained with intersecting line patterns did not appear to be explicable by torsional effects or the simple addition of tilted-line illusions.