Sensitivity to event timing in regular and irregular sequences: Influences of musical skill

In two experiments, the performance of listeners with different amounts of musical training (high skill, low skill) was examined in a two-alternative forced choice time-detection task involving simple five-cycle acoustic sequences. In each of a series of trials, all listeners determined which of two pattern cycles contained a small time change. Sequence context was also varied (regular vs. irregular timing). In Experiment 1, in which context was manipulated as a between-subjects variable, high-skill listeners performed significantly better than low-skill listeners only with regular patterns. In Experiment 2, in which context was manipulated as a within-subjects variable, the only significant source of variance was pattern context: All listeners were better at detecting time changes in regular than in irregular patterns. The results are considered in light of several hypotheses, including the expectancy/contrast model (Jones & Boltz, 1989).     

Classification and perceived similarity of compound gratings that differ in relative spatial phase

Discrimination studies suggest that two, and only two, channels encode relative spatial phase shifts in compound gratings (Bennett & Banks, 1991 ; Field & Nachmias, 1984). The more sensitive channel consists of even-symmetric filters and responds best to cosine phase shifts (e.g., 0°–180°); the other consists of odd-symmetric filters and responds best to sine phase shifts (e.g., 90°–270°). The present experiments investigated whether the two-channel model generalizes to suprathreshold perceptual tasks. Experiment 1 examined classification learning of compound gratings, consisting of a fundamental (f) and second harmonic (2f), that differed in 2f contrast and relative phase. Experiments 2 and 3 measured the perceived similarity off+2f gratings. The results of Experiment 1 were broadly consistent with the predictions of the two-channel model. Specifically, the classification data were best explained by assuming that classification was based on the responses of differentially sensitive even- and odd-symmetric filters. In Experiments 2 and 3, two-dimensional multidimensional scaling solutions provided a good account for the similarity judgments. In Experiment 2, Dimension 1 was strongly correlated with cosine phase, and Dimension 2 was moderately correlated with sine phase. In Experiment 3, cosine phase was again strongly rebated to Dimension 1, whereas the absolute value of sine phase was strongly related to Dimension 2. Overall, these results suggest that the two-channel model of phase discrimination provides a useful framework for interpreting classification and similarityjudgments of compound gratings.     

Persuasive Appeals and the Reduction of Skin Cancer Risk: The Roles of Appearance Concern, Perceived Benefits of a Tan, and Efficacy Information

This experiment compared the effectiveness of appearance-based messages focusing on the benefits of tanning and the efficacy of preventive measures on students' intentions to protect themselves against sun-induced skin damage. Subjects who were high or low on a dispositional measure of appearance concern responded to 1 of 4 essays providing either high or low benefits information, and high or low efficacy information. Overall, subjects low in appearance concern expressed greater intentions to take precautionary measures than did those high in appearance concern. Additionally, the low benefits of tanning message produced greater intentions to take precautions than did the high benefits message. The benefits results suggest 1 mechanism through which sun protection behaviors may be encouraged.     

The control of choice by its consequences

Five pigeons were trained on concurrent variable-interval schedules in which equal rates of reinforcement were always arranged for left- and right-key responses, but different overall rates were signaled by key colors. Sessions began with both keys lit yellow for the instrumental phase. If, after 20 s of this phase, the relative number of responses that had been made to the left key equaled or exceeded .75, both keys changed red for the contingent phase. The contingent phase arranged another concurrent variable-interval schedule for a further 20 s before the instrumental phase was reinstated. However, if preference in the instrumental phase did not exceed .75, the instrumental phase continued for a further 20 s before preference was again compared with the criterion. In Part 1, the reinforcer rate arranged in the instrumental phase was held constant at 4.8 reinforcers per minute, while the reinforcer rate arranged in the contingent phase was varied across conditions from 0 to 19.2 over five steps. In Part 2, reinforcer rates in the contingent phase were kept constant at 36 per minute, while reinforcer rates in the instrumental phase were varied from 0 to 36 over seven steps. Part 3 replicated Part 2 but used reinforcer rates in both phases that were one third of those arranged in Part 2. Measures of choice obtained by summing responses across presentations of the instrumental phase became more extreme toward the left key as the reinforcer rate obtained in the contingent phase was increased (Part 1) and as the reinforcer rate obtained in the instrumental phase was decreased (Parts 2 and 3). Changes in these measures of choice were accompanied by systematic changes in the relative frequency with which the criterion was exceeded. Changes in both these measures were correlated with changes in the relative frequency with which subjects responded exclusively to the left key. These results are discussed with respect to the two choices that were concurrently available in this procedure and the response alternatives that might constitute the concurrent operants in each choice.     

Book reviews

God, Reason, and Religions: new essays in the philosophy of religion. Eugene Thomas Long (Ed.), 1995. Dordrecht Kluwer Academic. 228 pp., hb. £67.50, ISBN 07 923333 810 3

Christians and Muslims: from double standards to mutual understanding. Hugh Goddard, 1995. London, Curzon Press. 200 pp., pb. £14.99, ISBN 0 7007 0364 0

Al‐Bayanat al‐Masihiyya al‐Islamiyya al‐Mushtaraka. Juliette Haddad (Ed.), 1995. Beirut, Dar al‐Mashriq. 207 pp., pb. n.p., ISBN 2 7214 5005 0

Muslim Writers on Judaism and the Hebrew Bible, from Ibn Rabban to Ibn Hazm. Camilla Adang, 1996. Leiden, E. J. Brill. 321 pp., hb. NLG140, ISBN 90 04 10034 2

Abū Ya qūb al‐Sijistani: intellectual missionary. Paul E. Walker, 1996. London, I. B. Tauris. 132 pp., rib. £35, ISBN 1 85043 921 4

The Cambridge Survey of World Migration. Robin Cohen (Ed.), 1995. Cambridge, Cambridge University Press. 570 pp., hb. n.p. ISBN 0 521 44405 5

Musulmans en Europe occidentals bibliographic commentée. Muslims in Western Europe: an annotated bibliography. Felice Dassetto & Yves Conrad (Eds), 1996. Paris, Editions L'Harmattan. 202 pp., pb., n.p., ISBN 2 7384 4126 2

Muslim Politics. Dale F. Eickelman & James Piscatori, 1996. Princeton, NJ, Princeton University Press. 235 pp., pb. n.p., ISBN 0 691 00870 1

Islam and the Myth of Confrontation: religion and politics in the Middle East. Fred Halliday, 1996. London, I. B. Tauris. 255 pp., £12.95, ISBN 1 85043 959 1

Nine Parts of Desire: the hidden world of Islamic women. Geraldine Brooks, 1995. New York, Doubleday. 255 pp. hb. £22.95, ISBN 0 385 47576 4

Aunt Safiyya and the Monastery. Bahaa’ Taher, 1996. Translated from the Arabic by Barbara Romaine. Berkeley, University of California Press. 124 pp., pb. n.p., ISBN 0 520 20075 6

Dreams of Trespass: tales of a harem girlhood. Fatima Mernissi, 1994. Reading, MA, Addison‐Wesley. 242 pp. pb., ISBN 0 201 62649 7

Lettres et message d'Algérie. P. Claverie, 1996. Paris, Karthala. 222 pp., pb. 120FF, ISBN 2 86537 657 5

Islamic Resurgence and Islamization in Malaysia. S. Batumalai, 1996. Perak, Malaysia. 279 pp., pb. RM 25/‐, no ISBN

Christian‐Muslim Relations: a case study of Sarawak, East Malaysia. Theodore Gabriel, 1996. Aldershot, Avebury. xiv, 133 pp., n.p., ISBN 1 85972 325 X

Muslim Communities in the New Europe. Gerd Nonneman, T. Niblock & B. Sjajkowski (Eds), 1996. Reading, Ithaca Press. 356 pp., hb. £35.00, ISBN 0 86372 192 3

Al‐Mughtaribun: American law and the transformation of Muslim life in the United States. Kathleen M. Moore, 1995. Albany, State University of New York Press. 211 pp., pb. $16.95, ISBN 0 7914 2580 0

The Landscape of Belief: encountering the Holy Land in nineteenth‐century American art and culture. [The Princeton Series in Nineteenth‐Century Art, Culture, and Society]. John Davis, 1996. Princeton, Princeton University Press. 264 pp., hb. $65.00, ISBN 0 691 04373 6     

Organizational reward systems: Implications for climate

This study investigated the role of systematically different organizational reward structures upon individual perceptions of the reward climate. Nurses in a naval hospital worked for the same supervisors but were subject to either tenure-contingent (N=73) or behavior-contingent (N=50) reward systems. No differences in perceived reward climate were found between the two groups. In the tenure-contingent group, job attitudes reflected individual characteristics rather than perceived climate. The opposite relationship was found for the behavior-contingent group.Support for this research was provided under Office of Naval Research Contract RR942-08-01 NR 170-915. Opinions expressed are those of the author. No endorsement by the Department of the Navy has been given, nor should it be inferred. Portions of the study were conducted while the author was at the Naval Health Research Center in San Diego. The author would like to thank R. J. Bullock, Mark C. Butler, L. R. James, and R. D. Pritchard for their helpful comments and assistance.