Comparison of timing and classical conditioning

Four experiments with rats investigated if the timing of a stimulus (sound) correlated with the strength of a conditioned response (CR) to the stimulus. The timing (effective duration) of the stimulus was measured using the peak procedure, similar to a discrete-trials fixed-interval procedure. The rats were trained so that their response rate reached a maximum about 40 s or 60 s after the onset of a light; the time of the maximum measured from the start of the light (peak time) was the measure of timing. On some trials, the light was preceded by a short (5 s) or long (20 s or 30 s) interval of sound. We assumed that the difference in peak time after long and short sounds reflected the timing of the sound--if the sound was timed, the longer sound would produce a lower peak time; if the sound was not timed, the two durations of sound would produce the same peak time. The CR was lever-pressing during the sound. The sound was treated in various ways: presented alone (Experiments 1, 3, and 4), followed by food (Experiments 1, 3, and 4), preceded by food (Experiment 3), and followed by food after 20 s (Experiment 4). Treatments that produced no timing of sound produced no CR, and treatments that increased (or diseased) timing also increased (or decreased) the CR. The results suggest that there is overlap between the mechanisms that produce time discrimination and the mechanisms that produce classical conditioning.     

The effects of feedback with chronically institutionalized mental patients

The ability of two female and one male chronically institutionalized adult mental patients to comprehend and retain feedback on individualized problem behaviors and the effect of that feedback on changes in the occurrences of those behaviors were examined. Feedback on five problem behaviors was provided to each subject within a small therapy group setting employing a multiple baseline across subjects experimental design. Comprehension and retention tests occurred two, five, and seven days following the feedback in the small groups, while the rates of the occurrences of the problem behaviors were time-sampled throughout the subjects' waking day via use of the Time-Sample Behavioral Checklist (Paul, 1987). Results indicated that, although there were no changes in the rates of occurrence, these subjects were able to retain and understand the feedback on their problem behaviors. Implications for further investigations and for the utility of feedback with chronically institutionalized adults are discussed.     

Inspecting pictures for information to verify a sentence: Eye movements in general encoding and in focused search

When we see combinations of text and graphics, such as photographs and their captions in printed media, how do we compare the information in the two components? Two experiments used a sentence-picture verification task in which statements about photographs of natural scenes were read in order to make a true/false decision about the validity of the sentence, and in which eye movements were recorded. In Experiment 1 the sentence and the picture were presented concurrently, and objects and words could be inspected in any order. In Experiment 2 the two components were presented one after the other, either picture first or sentence first. Fixation durations on pictures were characteristically longer than those on sentences in both experiments, and fixations on sentences varied according to whether they were being encoded as abstract propositions or as coreferents of objects depicted in a previously inspected picture. The decision time data present a difficulty for existing models of sentence verification tasks, with an inconsistent pattern of differences between true and false trials.