The filled-unfilled space illusion was investigated as a possible explanation for the asymmetry (difference in strength) between tails-out and tails-in versions of the Miiller-Lyer illusion. Previous work has shown that removal ofthe horizontal shaft makes both configurations look shorter, but affects them unequally and only partially reduces the asymmetry. In two experiments, illusion strength was varied by use of either different tail lengths or single-vs. double-ended figures. Subjects used method of adjustment with stimuli presented by computer. When the Miiller-Lyer was sufficiently weak, shaft removal had equal effects on both tails-in and tails-out configurations, but less effect on plain lines. This produced a reversal of the usual asymmetry, that is, tails-in was stronger than tails-out. It is concluded that the asymmetry is caused by the filledunfilled illusion. This may require reassessment of the view that the two Miiller-Lyer versions are different illusions.As early as 1909, Lewis argued that the Miiller-Lyer illusion could not be explained by any single principle. This view is now supported by a variety of studies, which have found differences between the tails-out and tails-in versions of the illusion. Of these, the best known difference is an asymmetry of strength. When tested separately, the tails-out (long) version is almost always stronger than the tails-in (short) version. In addition, the tails-out and tails-in versions respond differently to changes in such variables as the angle between shaft and tail, distance between tail tips (Sekuler & Erlebacher, 1971), and viewing duration (Erlebacher &Sekuler, 1974;Pollack, 1964). Finally, the two versions also respond differently to amputation of one or more of the tails (Day & Dickinson, 1976;Greist-Bousquet & Schiffman, 1981). Sekuler and Erlebacher noted that such differences are not easily handled by any single theory. They recommended that the two versions of the Millier-Lyer be treated as separate illusions.A slightly different strategy is to analyze the multiple causes of the illusion in such a way that factors responsible for the differences between versions can be separated from those that contribute similarly to both versions. The present study pursues this strategy by searching for the factor or factors that cause the asymmetry of strength.The most promising lead comes from Cooper and Runyon (1970), who reported that elimination of the horizontal shaft connecting the two sets of tails causes a I thank David Dexter and the Alma College Computer Center for technical support, Douglas Boyne and Steve Neff for help with data collection, and Carol Slater for a critique of the writing. Requests for reprints may be sent to Walter Beagley, Department of Psychology, Alma College, Alma, MI48801. 45 reduction in the strength of the tails-out illusion and an increase in the strength of the tails-in version. Although they did not include a plain-line control from which to measure asymmetry, the direction of change they reported should produce a reduc...

Rats that ate during hypothalamic stimulation were trained to press a lever for food only while receiving light signals from head-mounted lights. During stimulation, they pressed if the signal was visible to the eye contralateral to the electrode, but ignored the signal if it was visible only to the ipsilateral eye.

Rats subjected to inescapable shock subsequently were found to be helpless, unable to escape shock in an FR3 leverpress escape test. Rats which received equal amounts of escapable shock were unimpaired in their ability to escape, performing as well as controls given no pretest shock. One-half of the rats in each training group were then given bilateral lesions in the septal area, and all rats were retested. The lesions produced a large improvement in escape responding in the helpless group, but not in either of the nonhelpless groups. The results of this study suggest that septal lesions eliminate response inhibition caused by learned helplessness.

Software can be a curse. Like most people, I often feel guilty about all the software that sits idle in the box or on my hard drive because I have not yet had time to learn to use it. Even within the specialized area of psychology, there has been a lot of software development.Much of this has been described in Behavior Research Methods, Instruments, & Computers or can be found in on-line software directories such as CTI Psychology (Hammond & Trapp, 1991; www.psychology.ltsn.ac.uk/ ). So it comes as a surprise to me that I am going to argue that we need more software and more people writing it, especially more psychologists. The greatest need is software for research.There are two reasons why we need more programmers. The first is to ensure the continued health and growth of psychology. Any research field that fails to improve and invent new tools will not be able to recruit the best young minds and will eventually dry up. The second reason has to do with giving individualsthe greatest possible control of their own intellectual and professional lives. Researchers need to acquire at least journeyman-levelprogramming skills so that their careers will not be limited by the bounds of somebody else's imagination. What I am suggesting is that we need both: more people who publish software for general use and more people who can write their own software. Let us consider some objections to this thesis.Objection 1. Software creation should be left to wellfunded companies that can afford to develop and maintain quality products. It is true that a large company, employing a full time team of software developers, can produce a more professional looking product than a lone psychology professor working over summer break. The problem is that software is expensive to develop and the market is too small (Schneider, 1991). Large software companies can find other, more lucrative opportunities for their money and talent. As a result, most psychology research software has been written by individuals and small companies with limited resources. This means that development for psychology is slower than in the commercial mainstream and lags behind changes in hardware and operating systems.If large companies will not spend the money and small companies do not have it to spend, what can we do? Well, here is what we have done. First, we have relied on software that was written for a broader market. There is excellent software available for electronic instrumentation, digital imaging, and statistical analysis, because these functions are needed by scientists in all fields. Second, companies making software specifically for psychology research have survived by selling to the education market. Almost all of the research software packages for sale now have sets of experiments for use in undergraduate laboratory courses because, although still small, this market is much larger than that for pure research. This trend is good because it supports software that could not exist otherwise and it trains students on professional tools that they can cont...

Eye Lines is an experiment generator that differs markedly from the tachistoscope paradigm. Instead of recording reaction times and simple choices, it allows subjects to manipulate images and takes precise measurements of the results. This is useful for experiments in perception, rating scales, or any research needing analog input. A new version further refines a user interface designed to make the programs accessible to beginning students. The interface strategy includes the following: (1) the use of familiar structures, (2) the avoidance of rigid sequences, (3) a new graphic representation for the complexities of reconfiguring data, and (4) the use of contextsensitive defaults and concealment of advanced features. Eye Lines has been used to move beginning students quickly into designing and running their own experiments.The dominant paradigm in computer research tools for human experimental psychology has been that of the ta-