PubMed · 15940909
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A Welge-Lüssen. 2005-05-11. [Determination of olfactory function].. https://doi.org/10.1024/0369-8394.94.19.772
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In two experiments we investigated recognition and classification judgements using an artificial grammar learning paradigm. In Experiment 1, when only new test items had to be judged, analysis of z-transformed receiver operating characteristics (z-ROCs) revealed no differences between classification and recognition. In Experiment 2, where we included old test items, z-ROCs in the two tasks differed, suggesting that judgements relied on different types of information. The results are interpreted in terms of heuristics that people use when making classification and recognition judgements.
Following single stimulus training, responding during a generalization test tends to be distributed around the positive stimulus (S+). However, if participants are trained instead to discriminate the S+ from a negative stimulus (S-), the response gradient often shifts away from the S- and toward the opposite end of the stimulus continuum. In this experiment, the author examined the basis of gradient shifts with 72 college undergraduates. The research especially examined how gradient shifts are affected by the physical similarity of the S+ and the S- and by the ease with which the two stimuli can be compared. For the former manipulation, the author randomly assigned participants to either a control condition in which only the S+ was shown or a discrimination condition in which the S- was either near to or far from the S+ on the continuum. For the latter manipulation, the author randomly assigned participants to a condition in which S+ and S- presentations were separated by intervals of 1, 15, or 30 s. The results showed that marked shifts occurred when the S+ and S- were relatively similar, but temporal separations did not affect responding.
In order to study memory of the final position of a smoothly moving target, Hubbard (e.g., Hubbard and Bharucha, 1988) presented smooth stimulus motion and used motor responses. In contrast, Freyd (e.g., Freyd and Finke, 1984) presented implied stimulus motion and used the method of constant stimuli. The same forward error was observed in both paradigms. However, the processes underlying the error may be very different. When smooth stimulus motion is followed by smooth pursuit eye movements, the forward error is associated with asynchronous processing of retinal and extraretinal information. In the absence of eye movements, no forward displacement is observed with smooth motion. In contrast, implied motion produces a forward error even without eye movements, suggesting that observers extrapolate the next target step when successive target presentations are far apart. Finally, motor responses produce errors that are not observed with perceptual judgments, indicating that the motor system may compensate for neuronal latencies.