Biomedical subjects

L T DeCarlo

Publications and source records attributed to L T DeCarlo.

4 recordsLinked to original sources

PubMed1994

A dynamic theory of proportional judgment: context and judgment of length, heaviness, and roughness.

Subjects judged the length of lines, the heaviness of weights, or the roughness of sandpaper in 2 conditions. In 1 condition, they were instructed to make all their judgments relative to a long-term reference point, which consisted of a reference response and sensation. In the other condition, they were told to use a short-term reference point, namely, the response and sensation of the previous trial. A dynamic model of proportional judgment (L. T. DeCarlo, 1989/1990) predicts that the autocorrelation of successive responses will be larger for the latter instructions. This prediction was confirmed for the 3 continua. In addition, fits of a recently proposed dynamic regression model show that there is little or no effect of the previous stimulus intensity on the current response, whereas the results for an earlier model suggest a large contrast effect. The theory and experiments provide insight into judgmental and sensory processes in magnitude scaling.

Adult↗

PubMed1993

Estimating and testing autocorrelation with small samples: a comparison of the C-statistic to a modified estimator.

Huitema and McKean (Psychological Bulletin, 110, 291-304, 1991) recently showed, in a Monte-Carlo study, that five conventional estimators of first-order autocorrelation perform poorly for small (< 50) sample sizes. They suggested a modified estimator and a test for autocorrelation. We examine an estimator not considered by Huitema and McKean: the C-statistic (Young, Annals of Mathematical Statistics, 12, 293-300, 1941). A Monte-Carlo study of the small sample properties of the C-statistic shows that it performs as well or better than the modified estimator suggested by Huitema and McKean (1991). The C-statistic is also shown to be closely related to the d-statistic of the widely used Durbin-Watson test.

Biometry↗

PubMed1992

Intertrial interval and sequential effects in magnitude scaling.

The intertrial interval (ITI) was varied within subjects in magnitude estimation and cross-modality matching experiments. Fits of a recently proposed time series regression model show that the influence of the previous stimulus intensity on the current response decreases when the ITI is increased. The results can be interpreted as showing that an assimilative or additive perceptual or memory effect decreases with an increase in ITI. Fits of an earlier model, on the other hand, suggest that the influence of the previous stimulus intensity increases with an increase in ITI, which is counter to expectations. The new regression model (a) provides a simple explanation for the counterintuitive results obtained with the earlier model, (b) shows that assimilation in perception or memory can appear as contrast, and (c) reduces to a simpler model for longer ITIs.

Adult↗

PubMed1985

Matching and maximizing with variable-time schedules.

Pigeons were offered choices between a variable-time schedule that arranged reinforcers throughout the session and a variable-time schedule that arranged reinforcers only when the pigeon was spending time on it. The subjects could maximize the overall rate of reinforcement in this situation by biasing their time allocation towards the latter schedule. This arrangement provides an alternative to concurrent variable-interval variable-ratio schedules for testing whether animals maximize overall rates or match relative rates, and has the advantage of being free of the asymmetrical response requirements present with those schedules. The results were contrary to those predicted by maximizing: The bias it predicts did not appear.

Animals↗