Biomedical subjects

T L Kahan

Publications and source records attributed to T L Kahan.

4 recordsLinked to original sources

PubMed2001

Melatonin and sleep qualities in healthy adults: pharmacological and expectancy effects.

The impact of expectancy on melatonin's effects on sleep qualities was investigated. Both the pharmacological dose of 6 mg of melatonin and the expectation of receiving melatonin were predicted to improve subjective ratings of sleep qualities. The balanced placebo design varied 2 factors within-subjects: actual treatment and expected treatment. Adults (N = 53; 21 men and 32 women) between the ages of 26 and 71 years were administered either 6 mg of melatonin or a placebo for 8 nights. An instructional manipulation directed participants' expectations. Participants rated their nightly sleep experiences. Results revealed that feelings upon awakening differed between genders and that expecting melatonin increased ratings of sleep continuity. Most important, high ratings of "grogginess/tiredness" were associated with receiving melatonin, regardless of expectancy, as well as with receiving placebo when melatonin was expected. Overall, the findings underscore the need to consider expectancy and gender differences in research on melatonin and sleep experiences.

Adult↗

PubMed1997

Similarities and differences between dreaming and waking cognition: an exploratory study.

Thirty-eight "practiced" dreamers (Study 1) and 50 "novice" dreamers (Study 2) completed questionnaires assessing the cognitive, metacognitive, and emotional qualities of recent waking and dreaming experiences. The present findings suggest that dreaming cognition is more similar to waking cognition than previously assumed and that the differences between dreaming and waking cognition are more quantitative than qualitative. Results from the two studies were generally consistent, indicating that high-order cognition during dreaming is not restricted to individuals practiced in dream recall or self-observation. None of the measured features was absent or infrequent in reports of either dreaming or waking experiences. Recollections of dreaming and waking experiences were similar for some cognitive features (e.g., attentional processes, internal commentary, and public self-consciousness) and different for other features (e.g., choice, event-related self-reflection, and affect).

Adult↗

PubMed1996

Memory source confusions: effects of character rotation and sensory modality.

Eighty subjects viewed and visually imagined upright or rotated alphanumeric characters and later judged whether test characters were previously seen or imagined (reality monitoring). Identification and test characters were presented verbally or visually. When characters were identified and tested verbally, source confusions (misjudging a seen character as "imagined" and vice-versa) were infrequent and were comparable for rotated and upright characters. When characters were identified and tested visually, source confusions were more frequent and were influenced by character rotation. Memories for imagined characters were especially susceptible to source confusion. Also source confusions for seen characters increased when characters were rotated. These results are consistent with the proposal that increasing sensory similarity between perceived and imagined items increases source confusion and that perceived rotation generates cognitive operations similar to those generated when the subject imagines a character rotated.

Adult↗

PubMed1984

Dreams and reality monitoring.

Experiment 1 tested the counterintuitive prediction that memories for one's own dreams should not be particularly easy to discriminate from memories for someone else's dreams. Pairs of people reported dreams to each other that they had either dreamed, read, or made up the night before. On a test requiring subjects to discriminate events they had reported from those reported by their partner, subjects had more difficulty with real dreams than with dreams they read or made up. Experiment 2 provided evidence that real dreams do not simply produce overall weaker memories; the deficit for dreams was eliminated with more time to respond and with more detailed cues. In addition, subjects' ratings of various characteristics of their memories (e.g., vividness, personal relevance) indicated that dreams were not generally weaker or impoverished. The results are interpreted within the framework for reality monitoring described by Johnson and Raye (1981): Memories for real dreams are proposed to be deficient in conscious cognitive operations that help identify the origin of information generated in a waking state. At the same time, real dreams are embedded in a network of supporting memories that can be drawn on for reality monitoring decisions under appropriate circumstances. Finally, a comparison of recognition and recall indicated that dreams may leave persisting memories that are difficult to access via free recall.

Adult↗