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Biomedical subjects

J R Simon

Publications and source records attributed to J R Simon.

At least 91 records · Page 5Linked to original sources
PubMed1979

Effects of S-R mapping and response modality on performance in a Stroop Task.

Forty subjects performed a choice reaction time task in which the stimulus was the word Red or Green printed in either red or green ink. Subjects responded verbally in one block of trials and by key pressing in another block. For one group, ink color was the relevant cue, and for another group, the word was the relevant cue. Half of the subjects in each group were instructed to make the response that corresponded to the relevant cue (compatible S-R [stimulus-response] mapping); the other half were instructed to make the response that did not correspond (incompatible S-R mapping). In general, subjects who performed under compatible S-R mapping instructions reacted faster when the irrelevant cue corresponded to the response than when it did not. In contrast, subjects show performed under incompatible S-R mapping instructions reacted faster when there was a lack of correspondence between the irrelevant cue and the response than when there was correspondence. Results were consistent with a notion of logical recoding; that is, that instructing subjects to recode the relevant cue into the alternate color may have caused them to recode the irrelevant cue in the same logical manner. Results might also be interpreted to suggest that the Stroop effect is related to congruence between the relevant and the irrelevant cues rather than to correspondence between the irrelevant cue and the response.

Color Perception↗
PubMed1978

The effect of aging on the stages of processing in a choice reaction time task.

Two experiments were conducted to determine the effect of aging on the encoding and response selection stages of a choice reaction time task. In Experiment I, the Sternberg Additive Factor Method was used. Young (average age 20) and old (average age 73) subjects pressed a left- or right-hand key in response to the onset of an X or an O. The discriminability of these characters was manipulated so as to affect primarily the stimulus encoding stage. A tone presented simultaneously with the characters provided an irrelevant directional cue which previous research had indicated affects the response selection stage. The pattern of interactions of these manipulated variables with age suggested that aging affected stimulus encoding but not response selection. Results of Experiment II suggested that reducing stimulus discriminability may affect information processing prior to the encoding stage but confirmed the major conclusion of Experiment I that the encoding stage was the primary locus of the slowing which accompanied aging.

Acoustic Stimulation↗
PubMed1975

Further evidence for cholinergic habenulo-interpeduncular neurons: pharmacologic and functional characteristics.

Placement of high frequency lesions in the medial habenular area results in a large depletion of acetylcholine (ACh) levels, choline acetyltransferase (ChAc) activity, and high affinity choline uptake in the interpeduncular nucleus area (IPN) at 1, 3 and 7 days post-lesion. Areas adjacent to the IPN did not have a reduction in ChAc activity. The reduction in high affinity choline uptake was selective in that there was no change in the uptake of L-[3H]tyrosine or L-[3H]glutamic acid. Unlike the cholinergic septal-hippocampal neurons, there was no rise in ACh levels in the IPN 1 h after placement of lesion, or 30 min after administration of pentobarbital. While the IPN probably has a much denser cholinergic innervation than the hippocampus (as evidenced by much higher ACh levels, ChAc activity and choline uptake levels), it has only one-fourth as many [3H]QNB binding sites (a measure of cholinergic muscarinic receptors). This, some of the habenulo-interpeduncular neurons are probably cholinergic, and they may have pharmacologic and functional differences compared to the septal-hippocampal neurons.

Acetylcholine↗