Triple Conjunction Research Articles

Preattentive guidance of eye movements during triple conjunction search tasks: the effects of feature discriminability and saccadic amplitude.

Eye movements were monitored during the performance of triple conjunction search tasks. Stimuli varied in color, shape, and orientation. Across trials, the target was either present or absent, and displays consisted of 6, 12, or 24 stimuli. Stimulus discriminability was manipulated for the shape dimension, with half of the participants seeing displays of Es and Fs (low-discriminability [LD] condition) and half seeing displays of Cs and Ts (high-discriminability [HD] condition). Participants in both conditions performed two search tasks. In the single-feature (SF) task, the target stimulus shared one feature with each of the distractors, whereas in the two-feature (TF) task, it shared two features with each distractor. An examination of saccadic endpoints revealed that participants were more likely to fixate on distractor stimuli sharing color (SF task) or color and shape (TF task) with the target. This was a robust finding, being observed across participants, saccades of different amplitudes and sequential position, and following short and long latencies to move. The extent to which participants made use of shape information increased with discriminability.

Star of Bethlehem

The biblical Star of Bethlehem, which heralded the birth of Jesus Christ, is only mentioned in the Gospel of St Matthew 2. The astrologically significant 7 bc triple conjunction of Jupiter and Saturn in the constellation of Pisces is the most likely candidate, although a comet/nova in 5 bc and a comet in 4 bc cannot be ruled out. There is also the possibility that the star was simply fictitious.

A signal detection model predicts the effects of set size on visual search accuracy for feature, conjunction, triple conjunction, and disjunction displays

Recently, quantitative models based on signal detection theory have been successfully applied to the prediction of human accuracy in visual search for a target that differs from distractors along a single attribute (feature search). The present paper extends these models for visual search accuracy to multidimensional search displays in which the target differs from the distractors along more than one feature dimension (conjunction, disjunction, and triple conjunction displays). The model assumes that each element in the display elicits a noisy representation for each of the relevant feature dimensions. The observer combines the representations across feature dimensions to obtain a single decision variable, and the stimulus with the maximum value determines the response. The model accurately predicts human experimental data on visual search accuracy in conjunctions and disjunctions of contrast and orientation. The model accounts for performance degradation without resorting to a limited-capacity spatially localized and temporally serial mechanism by which to bind information across feature dimensions.

Visual Search and the Older Adult: Not all is Lost

Plude and Doussard-Roosevelt (1989) reported age-related search slope differences in a conjunction search task but not in a feature search task. According to Feature Integration Theory (Treisman & Gelade, 1980), older adults may suffer an impairment in the feature integration mechanism required for conjunction searches. We extend this work by examining age-related differences a series of feature, conjunction, and triple conjunction search tasks. The results of the feature and conjunction search tasks support the previous findings. However, the results of the triple conjunction search task suggest that the conjunction search impairment is not universal. As the triple conjunction search results are difficult to accommodate within Feature Integration Theory, the results are discussed within the framework of the Guided Search model of visual selective attention.

Why are conjunctive categories overextended?

Recent experiments have suggested that subjects tend to overextend conjunctive categories (J. A. Hampton, 1988). We present a series of four experiments that confirm this finding. In Experiment 1, we use Hampton's response scale, on which subjects rate both membership and typicality. In Experiment 2, we find that subjects still overextend their categories when they judge membership alone. In Experiment 3, we introduce more response options and conclude that the tendency to overextend is not an artifact of an insufficient range of possible responses. We propose an explanation of overextension that we term the compensation hypothesis: The more categories that make up a conjunction, the more leniently membership is judged. We argue that this is a result of having to make best fit judgments for multiple constraints in real life. We test this hypothesis in Experiment 4, which uses conjuncts of three categories. As predicted, we find that overextensions are greater with triple conjunctions than in appropriate controls in which two categories are combined or categories are judged alone. We consider the theoretical implications of a compensation strategy for categorization.

Guided search: An alternative to the feature integration model for visual search.

Subjects searched sets of items for targets defined by conjunctions of color and form, color and orientation, or color and size. Set size was varied and reaction times (RT) were measured. For many unpracticed subjects, the slopes of the resulting RT X Set Size functions are too shallow to be consistent with Treisman's feature integration model, which proposes serial, self-terminating search for conjunctions. Searches for triple conjunctions (Color X Size X Form) are easier than searches for standard conjunctions and can be independent of set size. A guided search model similar to Hoffman's (1979) two-stage model can account for these data. In the model, parallel processes use information about simple features to guide attention in the search for conjunctions. Triple conjunctions are found more efficiently than standard conjunctions because three parallel processes can guide attention more effectively than two.

Kepler's View of the Star of Bethlehem and the Babylonian Almanac for 7/6 B.C.

Modern discussion of what identifiable astronomical phenomenon lies behind the biblical story of the so-called Star of Bethlehem was effectively begun by the astronomer Johann(es) Kep(p)ler (1571–1630), mathematician to Rudolph II, Holy Roman Emperor 1576–1612. In the years 1604–5 a supernova appeared in the constellation Ophiuchus and excited considerable discussion in Europe. Kepler kept a detailed record of his observations of the star. In the preceding year, 17 December 1603, at Prague he had also witnessed a conjunction of the planets Jupiter and Saturn with Mars moving into the vicinity soon after, which interested him in his capacity as court astrologer. The supernova appeared in the neighbourhood of these three planets. In medieval times the conjunction of Jupiter and Saturn, known as the “great conjunction” (recurring only once every 19·86 years on average), was regarded as of great astrological significance. Kepler calculated that a similar conjunction with Mars moving into the vicinity soon after had occurred in the year 7 B.C. = Julian year 39. On that occasion the conjunction had been a triple conjunction, a very much rarer event than the normal single conjunction.

Astronomical Dates in Shang and Western Zhou

This article reports the discovery in the Bamboo Annals of verifiable accounts of the general conjunctions of planets witnessed by Shang and Zhou dynasty observers, which occurred in 1576 and 1059 B.C. Besides exploring the connections between the planetary phenomena and mythologized accounts of the same events in Zhou and Han texts, the significance of these astronomical dates is discussed in reference to the events surrounding the Zhou Conquest of Shang and the founding of the Shang dynasty. The investigation proposes that the Shang and Zhou astrologers were astute observers of the motions of the planets and that there are a number of Zhou traditions, such as those concerning visitations of the Phoenix, which are intimately associated with certain planetary periods. In addition, it is suggested that the concept of the Mandate of Heaven as a physical manifestation of Heaven's will and that of its transfer to virtuous rulers at 500 year intervals both derive from the period of the so-called Triple Conjunctions accurately recorded in the Bamboo Annals.

The Star of Bethlehem

The Star of Bethlehem was probably a triple conjunction of Saturn and Jupiter in the constellation of Pisces, the significance of which was only obvious to the Magi of Babylonia. This occurred in 7 BC and events indicate that Jesus Christ was probably born in the Autumn of that year, around October, 7 BC.