Six homing pigeons were trained on a variety of concurrent-chains schedules in which the initial links were equal variable-interval schedules and the terminal links were fixedinterval schedules. Both terminal-link and initial-link schedules were systematically varied.The results showed that preferenlce for a particular terminal-link schedulle combination was greater, the shorter the initial-link schedules. The data closely matched predictiolns from the model of choice suiggested by Davison and Temple (1973), but did not match predictions from two other models. An alternative method for analyzing coictirrent-chains performance by assuming that the schedItle consists of both chained schedlules and suiccessive, discriminated components that comprise multiple schedules, was suggested.In concurrent-chains sclhedules (Autor, 1960) that systematically varied initial-link parameters (Fanitino, 1969). This experiment showed that preference for VI schedules, as measured by the ratio of the ntlml)ers of initial-link responses, was more extreme with shorter and equial initial-link sclheduLles. However, recent work (e.g., MacEwen, 1972) has shown that Fantino's (1969) METHOD StubjectsSix lhoming pigeons, which had previously been trained on multiple schedules, were maintained at 80% +15% of their free-feeding body weights, and were numbered 131 to 136.

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Although terrorism is not a novel phenomenon there are valid reasons for supposing that current terrorist operations pose a greater potential threat to liberal democracies than their historical forebears did. However, while many o f the reasons for this change i n terrorist potential are grounded in physical technological innovation and its consequences, the solutions, either long-term or crisis oriented, are inescapably rooted in behavioural considerations.Current anti-terrorist measures tend to rely excessively on physical technological solutions and are therefore unable to provide useful answers to many of the important questions surrounding terrorism. Since we are dealing with human behaviour it i s vital that we assess the contribution that can be made by psychology to the resolution o f the problems posed by terrorism. This paper outlines some of the important areas in which psychology has, or could have, a significant role to play in the investigation and control of terrorist activities. The Nature of Contemporary TerrorismAlthough terrorism is not a novel phenomenon, there are valid reasons for supposing that current terrorist operations pose a greater potential threat to liberal democracies than did their historical forebears to the governments of their times. Contemporary political terrorism is significantly different from past variants both in terms of philosophy and tactics, and in the social and political environment in which it operates. Many of the differences are directly or indirectly a consequence of technological change, with the most obvious relevant developments being in the fields of transport, communications (particularly as applied to news gathering and distribution), and weaponry.The advent of the jet airliner and the fact that it is easily accessible to large numbers of people has brought with it mobility and a significant increase in the range of possible targets within the reach of any particular group or individual. The emergence of transnational terrorism involving terrorists of different nationalities planning,

This work outlines the important considerations of policy that confront a democratic state in trying to combat terrorism and at the same time remain democratic. Part I of this book, provides the reader with a comprehensive introduction to the definition, history, theory, operation and effects of terrorism as an essential background to policy analysis. Part II analyses counter-terrorist policies. It begins by outlining basic policy choices and then looks at specific policy areas such as the role of intelligence agencies, the use of the armed forces, the development of anti-terrorist legislation and international treaties, and the issue of regulation of media reporting of terrorist incidents. Developments in the strategic dimension of terrorism are discussed in chapters on the importance of hostage takings to international terrorism and issues surrounding state involvement in international terrorism. In the preparation of this second edition, Grant Wardlaw has considerably expanded the second part of the book, focusing firmly upon the international policy consequences of prevalent developments within international terrorism.

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