Methylphenidate and stimulus control of avoidance behavior

The introduction of a warning signal that preceded a scheduled shock modified the temporal distribution of free-operant avoidance responses. With response-shock and shock-shock intervals held constant, response rates increased only slightly when the response-signal interval was reduced. The result is consistent with Sidman's (1955) findings under different conditions, but at variance with Ulrich, Holz, and Azrin's (1964) findings under similar conditions. Methylphenidate in graded doses increased response rates, modifying frequency distributions of interresponse times. Drug treatment may have disrupted a "temporal discrimination" formed within the signal-shock interval. More simply, methylphenidate influenced response rates by increasing short response latencies after signal onset; this effect was more prominent than the drug's tendency to increase the frequency of pre-signal responses. When signal-onset preceded shock by 2 sec, individual differences in performance were marked; methylphenidate suppressed responding in one rat as a function of increasing dose levels to a greater degree than in a second animal, but both subjects received more shocks than under control conditions.     

Adjusting fixed-ratio schedules in the squirrel monkey

On an adjusting schedule of reinforcement, a parameter of the schedule is varied as a function of some characteristic of the animal's performance. In Experiment I, the fixed-ratio response requirement was varied as a function of the time that elapsed before the animal started responding in each fixed-ratio (initial pause). When initial pauses were shorter than a specified duration, the response requirement was increased; when they were longer than the specified duration, the response requirement was decreased. Specified durations of 1, 2, 4, 8, and 15 min were studied. The average response requirement maintained by each monkey was directly related to the length of the specified duration of initial pause. In Experiment II, the fixed-ratio response requirement was constant, but reinforcement occurred only when the initial pause was longer than a specified duration. The average durations of initial pauses were directly related to the length of the specified duration and to the response requirement. Meprobamate consistently decreased the average durations of initial pauses.     

College Freshman Performance: Summer Entrants vs. Fall Entrants

Entering college students and their advisors—high school and college personnel—frequently assert that the student will do better academically by entering college during the summer term rather than during the fall term with its many extracurricular activities. Comparing the academic performances over the first two quarters of 320 summer quarter entrants with 320 fall quarter entrants at the University of Tennessee yielded no significant differences for season entered. The ACT composite score for each student was held constant by using analysis of covariance. Significant differences for year entered—1962 or 1963—were apparently a function of the lack of reliability in grading practices. The academic performance of entering students did not benefit from summer quarter entrance.     

Explaining the behaviour of random ecological networks: the stability of the microbiome as a case of integrative pluralism

Synthese - Explaining the behaviour of ecosystems is one of the key challenges for the biological sciences. Since 2000, new-mechanism has been the main model to account for the nature of scientific...     

The curious case of spillover: Does it tell us much about saccade timing in reading?

In completing daily activities, the eyes make a series of saccades by gazing at stimuli in succession. The duration of gaze on each stimulus has been used to infer how the initiation of a saccade is timed relative to the underlying mental processing. In reading, gaze dwells longer on a word that occurs infrequently in English text (low frequency) than on a more frequent word (high frequency), but also on the following word, which is referred to as spillover. Accounts of spillover attribute it to mechanisms of lexical access. A low-frequency word n is assumed to delay the onset of cognitive processing of word n+1 more than it delays the saccade to n+1, leaving more processing to be done on n+1 once it is fixated. We tested this assumption by having participants perform a series of speeded lexical decisions on a linear array of letter strings spaced 5° apart, using low- and high-frequency words to vary the lexical difficulty. Lexical decision adds a response selection stage that is absent in reading, which should eliminate differential effects on saccades and cognitive processing. Nonetheless, we found the typical pattern of lengthened gaze duration and spillover for low-frequency words, with effects that were consistent in magnitude with those seen in studies of reading. These data challenge existing accounts of spillover and argue against the idea that reading has a unique interaction with oculomotor control. Instead, the similarity of our gaze patterns to those of reading suggests a common pattern of saccade initiation across tasks.     

"THE DUNGEON OF THYSELF": The Claustrum as Pathological Container

The author discusses the claustrum as an aspect of pathological containment within inner space and its relation to Bion's (1962a, b) container—contained concept. Having outlined the early psychoanalytic conceptual foundations of claustrophobia and the claustrum, the author charts the term from its introduction by Erikson in 1937 through its divergent developmental trajectories within the conceptual vocabulary of the classical, Independent and Kleinian schools up to Meltzer's (1992) contemporary reworking. The vicissitudes of the transmission of ideas within and between these groups is stressed, Esther Bick's work being particularly highlighted as an example of a nodal intellectual influence. The claustral space within the physical or internal object body, its internal structuralisation, and the impairments in quality of psychic life of the selves that seek to inhabit such spaces, entered through intrusive projective identification, are highlighted. Developmental and psychopathological claustrum manifestations are discussed, particularly fear, separation, problems mourning and claustrophobia. A reciprocal and hierarchical avatar relation between the claustrum and the container is proposed.