An event-coder for evoked potential studies

A device is described which has 10 input and 2 output lines. Grounding an input causes a pulse with a specific amplitude, polarity, and duration to appear on one of the output lines. Pulse parameters can be set by front-panel controls. Thus, 10 distinct events can be coded by associating a unique pulse with each event. These pulses can be recorded on one (or two) channels of a magnetic tape recorder for subsequent processing. The use of this coder in the study of event-related potentials is described.     

Redistributing control between the elements of a compound stimulus

Twenty-eight pigeons were given discrimination training. Four groups were run in which for 0, 2, 4 and 9 sessions of training colour was an irrelevant cue and tone was relevant. Generalization tests were given in extinction; the training colour (C₁) and another colour (C₂) were presented with tone (T) and noise (N). Responding to these four stimulus combinations, TC₁, TC₂, NC₁ and NC₂, allowed the assessment of control by colour and tone. A reduction of control by colour and an increase in control by tone were found to be positively related to the amount of training with colour irrelevant. Tests showed a strong inverse relationship between control by colour and tone.     

Interaction of fear effects with habit strength

Four groups of rats received 0, 3, 6 or 9 days of overtraining after having reached stable performance on a continuous reinforcement bar pressing schedule. Half the subjects in each group had previously been designated emotionally reactive or non-reactive in terms of defecation rates in an open-field test. Following training, there were four test days in which bar pressing in each group was examined in the presence or absence of white noise. The major findings were that, in both the reactive and non-reactive groups, white noise produced a fear reaction which significantly depressed bar pressing at low levels of habit strength while having an energizing effect at higher levels. The results were interpreted as supporting Bardach's (1960) hypothesis that anxiety introduced early in practice is more disruptive than when introduced late in practice.     

Reinforcement of visual attending in classrooms for deaf children

The efficacy of immediate tangible reinforcement in increasing appropriate visual attending for entire classes of deaf children was examined. The subjects were three classes (seven children each) in a residential school for the deaf. Boxes were installed on each child's desk, with lights that were flashed immediately contingent upon 10 sec of visual attending. Light flashes were backed up by M & M's, cereal bits, or tokens. In two of the classes, extinction sessions were also scheduled. For all classes, the reinforcement procedure increased visual attending by 50% or more, maintaining it at rates above 82%. Withdrawal of tangibles decreased attending back to baseline levels. The results support analysis of attending as operant behavior and demonstrate the applicability of reinforcement procedures in modifying these behaviors for young deaf children in a classroom setting.