Development and maintenance of attack in pigeons during variable-interval reinforcement of key pecking

Key-peck responses of two pigeons were maintained on variable-interval schedules of food reinforcement in the presence of a stuffed pigeon to study the characteristics of attack induced by that schedule. The mean interval of the schedule was increased from 15 sec to 600 sec in eight steps before an intermediate interval was reintroduced. The principal characteristics of attack were: (1) substantial attack first occurred on a variable-interval schedule of 90 sec in one pigeon and at 180 sec in the other, (2) the highest attack rates occurred on variable-interval schedules of 300 sec and 600 sec, (3) attack rate generally increased to a maximum and then decreased to a lower level across sessions at each schedule, (4) attacks developed a postreinforcement locus across the initial sessions on all schedules and, except on variable-interval schedules of 300 and 600 sec, occurred primarily in the postreinforcement period during extended training, (5) attack rates and key-peck rates were not recovered when the intermediate-length schedules were reintroduced, and (6) attack rate and key-peck rates were negatively correlated. Except for the fact that the maximum attack rates occurred at interfood intervals of 300 and 600 sec, and that attack and key-peck rates were negatively correlated, these findings have counter-parts in experiments with other reinforcement schedules.     

Erwiderung

Ohne Zusammenfassung     

Distinguishing representation deficits and processing deficits in a case of acquired dysgraphia

The same acquired disorder of spelling may be due to deficits affecting lexical representations of word spelling or deficits affecting the mechanisms that process those representations. This study sought to distinguish these possibilities in a dysgraphic patient. The integrity of the patient's lexical orthographic representations was assessed by having him decide whether or not pairs of words presented auditorily rhymed. Although the patient was impaired on a variety of spelling tasks and with all types of stimulus material, he showed a normal effect of spelling on the rhyme task. Like normal subjects, he was faster at deciding that words rhymed when they were spelled similarly (e.g. tool-cool) than when they were spelled dissimilarly (e.g. rule-cool) and slower at deciding that words did not rhyme when they were spelled similarly (e.g. toad-broad) than when they were spelled dissimilarly (e.g. code-broad). Therefore, as the patient's lexical representations of word spelling seemed to be generally intact, his spelling problems were probably due to difficulty in processing those representations.     

Effects of directiveness of instructions and surveillance on the production and persistence of children's donations

All subjects earned tokens for correct size judgments and observed a model who had previously earned tokens at the same task donate some of her earnings. Children were subsequently given an opportunity to donate some of their tokens to children at another school. The opportunity to give occurred in presence (surveillance) or absence of the experimenter and after being presented with either directive (you must give) or permissive (you can give if you want to) instructions. Directive instructions and surveillance both produced greater initial giving for all children. In a second session with no modeling, no surveillance, and no further instructions, earlier directive instructions also produced greater persistence of giving for all children. Permissive instructions produced greater reductions in giving over time for boys than for girls. The present findings suggest that directive instructions produce greater initial giving and that donating persists better under these more explicit conditions.     

CROSS-LANGUAGE DIFFERENCES IN DICHOTIC LISTENING*

Greater right ear advantage in dichotic listening to English-spoken digits among English-speakers than among Japanese- and Hebrew-speakers (Hatta and Dimond 1981; Nachshon 1986) was attributed either to effects of linguistic properties of the respective native languages, or to the sequence of language acquisition. In order to evaluate the two alternative hypotheses, 112 English-Hebrew and 140 Hebrew-English bilinguals recalled a series of three-digit dichotic sets. Differential ear advantages were expected on the basis of the two hypotheses. Data analysis showed, however, that while recall was better for digits spoken in the native than in the non-native languages, no significant differences in right ear advantage between the two groups were found. Procedural effects might account for this result.     

Sharing as Hope and Celebration

And no one puts a piece of unshrunk cloth on an old garment, for the patch tears away from the garment and a worse tear is made. Neither is new wine put into old wineskins; if it is, the skins burst, and the wine is spilled, and the skins are destroyed; but new wine is put into fresh wineskins and so both are preserved. (Matt. 9:16–17)