The relationship of estimated comprehensibility to the rate of connected speech

The relationship between subjective estimates of the comprehensibility of connected, freerunning speech and rate of speech was investigated for each of two types of time-compressed speech: pitch-varying speeded speech and pitch-normalized compressed speech. The midpoints of the resulting functions approximated the values obtained by a previously described speechrate tracking method. For equivalent degrees of comprehensibility, rates were higher for compressed speech than for speeded speech, indicating that estimates are sensitive to the intelligibility of speech. Subjective estimates of comprehensibility of time-compressed speech provide a means of assessing the itelligibility of connected speech.     

One-trial overshadowing

Two experiments on conditioned suppression in rats examined the extent to which conditioning to a tone was overshadowed by the presence of a light. When animals received four conditioning trials, a light of moderate intensity significantly overshadowed the tone. On the first trial of conditioning, however, the light had no effect on conditioning to the tone, unless (Experiment I) its intensity was increased, or (Experiment II) it occurred in closer temporal contiguity to reinforcement than the tone. The results establish that overshadowing can occur on the first trial of conditioning, contrary to the predictions of several theories, but suggest that this may be for different reasons from those operating to produce overshadowing over a series of conditioning trials.     

Signalled free-operant avoidance of shock by pigeons pecking a key

Two pigeons were trained to peck a key under a free-operant avoidance schedule. Then, changes in key color signalled the beginning (safe period) and the end (warning period) of the response-shock interval, with a response required to change the key color. Finally, a change in key color signalled the warning period and either a response or a shock reinstated the safe stimulus. During signalled avoidance, response rate was higher during the warning stimulus than during the safe stimulus. More responding tended to occur in the warning stimulus when it was terminated by either a response or a shock than by only a response. In either procedure, response latency during the warning stimulus was a function of the duration of the warning stimulus. In general, response and shock rate were higher during unsignalled than during signalled avoidance. When the warning stimulus was brief, the results were similar to those of unsignalled avoidance. These results confirm previous findings with pigeons, are in general agreement with data provided by other species in studies of signalled avoidance, and thereby indicate the transituationality of the key-pecking operant.     

The role of anionic, imidic and amidic forms in structure-activity relationships. Conjugation and bacteriostatic activity in sulphonamides.

The electronic structures of anionic, imidic and amidic forms of sulphonamides were investigated and compared by means of I.R., Raman and U.V. spectroscopy. Indices reflecting the electronic situation of the common moiety p-H2N-C6H4-SO2 was a whole, although not necessarily related, physically, to any event taking place in the biological processes, were found to correlate with the in vitro bacteriostatic activity of the specific individual forms. The influence of N1-substituents both on the SO2 electronic features and on the coupling between the para amino group and the phenyl ring was discussed. It resulted that the most active chemical species, in this class of compounds, are characterized, electronically, by the most electron-rich common moiety and, in particular, by the most negative oxygens in the SO2 group and the most available (less engaged) lone-pair in the rho-amino group. These conclusions give a new settlement both to the problem of resonance and to the relation between resonance effects and bacteriostatic activity in this class of compounds.