Spontaneous and learned turning behaviour in food- or water-restricted hooded rats

Some laboratory studies have suggested that whereas food restriction in animals leads to response alternation (behavioural flexibility), water restriction induces perseverative, stereotyped responding. Hooded rats, restricted to 1 hour per day access to either food or water, were tested on a radial-arm maze (using a procedure that eliminates algorithmic response strategies), for alternation in a 3-arm maze (both when the maze was familar and unfamilar, and with or without differential reward) and a 2-choice maze in which some animals were taught to alternate direction of turn, and others to perseverate. Both groups performed the radial-arm maze task competently and spontaneously alternated at a high rate. In the learned task, food-restricted rats were slower than water-restricted to reverse a consistent direction of turn; in the alternation condition, water-restricted rats developed a temporary, but strong, directional bias when making their first choice each day. Water-restricted subjects took water more readily than food-restricted took food when initially introduced to the apparatuses, but there was no consistent difference in motivation in the two conditions. The results provide little support for the notion that distinct cognitive-motivational states or behavioural strategies are induced by food- and water-restriction.     

Suicide in the Subway: Psychodynamic Aspects*

ABSTRACT: Fifty-one cases of suicide attempts in the subway have been investigated to examine the question of whether the method used has psychodynamic significance or is merely adventitious. We found that no single characteristic distinguished subway suicide from all other suicide modalities, although as a group the subway cases had a higher proportion of psychotic and previously suicidal patients than other series quoted in the literature. However, there were important differences between subway suicide cases seeking a “traumatic” death (jumping in front of a train; lying across the track awaiting destruction) and those seeking a “nontraumatic” death (electrocution on the live “third rail”). The traumatic group had histories of exposure to violence, other traumatic suicide attempts, hostile or destructive delusions, and many “destroy” words on psychological test protocols. The smaller nontraumatic group had no such history of exposure to violence; their previous suicide attempts were nontraumatic; delusions, when present, were not menacing; and the psychological tests showed more “escape” words than “destroy” words.     

Psychological effects of urban and rural domiciles

The purpose of the investigation was to examine some problems concerning physical and mental differences between the population born and living in a large urban community (Group A), those who had moved from rural to urban setting (Group B), and stationary rural subjects (Group C). Each group consisted of 100 men between the ages of 19–25 years (total N= 300).     

Skill Acquisition and the LISP Tutor

An analysis of student learning with the LISP tutor indicates that while LISP is complex, learning it is simple. The key to factoring out the complexity of LISP is to monitor the learning of the 500 productions in the LISP tutor which describe the programming skill. The learning of these productions follows the power-law learning curve typical of skill acquisition. There is transfer from other programming experience to the extent that this programming experience involves the same productions. Subjects appear to differ only on the general dimensions of how well they acquire the productions and how well they retain the productions. Instructional manipulations such as remediation, content of feedback, and timing of feedback are effective to the extent they give students more practice programming, and explain to students why correct solutions work.