Stimulus generalization as a function of contextual stimuli.

Helson, Harry; Avant, Lloyd L.

doi:10.1037/h0024319

Cited by 28 publications

(30 citation statements)

References 1 publication

(1 reference statement)

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“…Typically, reinforcement gradients show a central tendency effect, which occurs when the peak of the gradient is located at the central stimulus value of the continuum even though that value is not the S D (e.g., Helson & Avant, 1967;Thomas & Bistey, 1964;Thomas & Jones, 1962;Thomas, Strub, & Dickson, 1974). The degree of the central tendency effect is modified by the presence and location of an extinction-correlated S ⌬ on the continuum (e.g., Newlin, Rodgers, & Thomas, 1979;Thomas, Mood, Morrison, & Wiertelak, 1991;Thomas, Svinicki, & Vogt, 1973).…”

Section: Resultsmentioning

confidence: 99%

Stimulus Control and Generalization of Point‐loss Punishment With Humans

O’Donnell¹,

Crosbie²,

Williams³

et al. 2000

J Exper Analysis Behavior

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Two experiments demonstrated stimulus control and generalization of conditioned punishment with humans. In both studies, responses first were reinforced with points exchangeable for money on a variable-interval schedule in the presence of one line length (S D ). Next, a second line length was introduced, and point loss followed every response in the presence of that line (S ). In the final D p training condition, points were deducted at session end. Response rate was lower in the presence of the S despite equal rates of points for money in the presence of both stimuli. In generalization D p testing for Experiment 1, the two lines were included in a 10-line continuum; S fell in the middle D p and the trained S D was at one end. Lines were presented randomly, and point delivery and loss contingencies were as in training but with points available in the presence of all lines. For all subjects, response rates were lowest around S and increased towards the S D end of the continuum. Because

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Section: Resultsmentioning

confidence: 99%

Stimulus Control and Generalization of Point‐loss Punishment With Humans

O’Donnell¹,

Crosbie²,

Williams³

et al. 2000

J Exper Analysis Behavior

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“…On other stimulus dimensions, asymmetrical series of test stimuli have been shown to produce a central tendency shift. Thomas and Jones (1962), with wavelengths of light, and Helson and Avant (1967), with stimulus size, have shown that following exposure to a skewed distribution of test stimuli, participants respond more to stimuli closer to the AL or to the mean of the test series than they respond to the original S . In the present experiment, we attempted to produce a central tendency shift with stimulus duration.…”

Section: Methodsmentioning

confidence: 99%

Temporal generalization and peak shift in humans

Bizo¹,

McMahon

2007

Learning & Behavior

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Three experiments investigated temporal generalization in humans. In Experiment 1, a peak shift effect was produced when participants were given intradimensional discrimination training. In Experiment 2, after training with a standard S and generalization testing with an asymmetrical series of durations, generalization gradients moved toward the prevailing adaptation level. In Experiment 3, generalization gradients showed a central tendency shift and moved away from the S and toward the mean of the test series (of 11 stimulus durations) after participants received training with S and S durations that in one condition were the 2nd and 4th and in another condition were the 4th and 2nd stimuli in the series, respectively. The results were inconsistent with an absolute account of peak shift but were consistent with an adaptation level account of peak shift.

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“…The research was supported by NIH Research Grant HD-03486 and Training Grant MH-I0427 under the direction of David R. Thomas. The paper is respectfully dedicated to the memory of Harry Helson, Requests for reprints should be sent to David R. Thomas, Department of Psychology, University of Colorado,Boulder,Colorado 80309. dimensions, including size-area (Helson & Avant, 1967), weight (Hebert, Origlio, & McGuirk, 1972), brightness (Thomas, Strub, & Dickson, 1974), and line angle (Thomas & Thomas, 1974).…”

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confidence: 99%

The central tendency effect in stimulus generalization: Effects of establishing a “preexperimental” frame of reference

Newlin

Rodgers

Dickson

et al. 1978

Perception & Psychophysics

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An experiment was performed to test the hypothesis that in a voluntary generalization task subjects encode the training stimulus (TS) in relation to the adaptation-level (AL) prevailing at the time of TS presentation. If so, then during a subsequent generalization test the point of maximal generalized responding should bear this same relationship to the AL of the generalization test series. To test this hypothesis, three major groups of subjects (n = 80) were given preexposures with dim lights (low preexperimental AL group), bright lights (high preexperimental AL group), or no preexposure (control group). Next, half of each group was exposed to a TS and a subsequent generalization (recognition) test including this brightness and four others. The other half of each group was exposed to the same TS and subsequent generalization stimuli, but their task was to rate the stimuli on a 7-point bright-dim scale. This provided AL measures which could be correlated with generalization performance in the comparable generalization groups. The preexposure condition was successful in producing the expected low or high preexperimental ALs, as reflected in different ratings of the TS when it was presented. Furthermore, these effects persisted throughout testing, as evidenced in ALs (i.e., rating scale midpoints) which reflected the preexposure condition. Finally, the difference' between the point of maximal generalized responding and the AL of the generalization test series was highly and significantly correlated with the difference between the original rating of the TS and scale midpoint. This supports the major experimental hypothesis of the study. Thomas and Jones (1962), in a study of voluntary stimulus generalization, found that the location of the training stimulus within the test series had a marked effect on the symmetry of the resulting generalization gradients. Their subjects were given a 6O-sec exposure to a 525-nm training stimulus (TS) with instructions to remember the stimulus so that they could identify it during a subsequent wavelength generalization test. The location of the TS in the test series was systematically varied, with the TS being in the center position of the test series for one group and asymmetrical (i.e., displaced from the center) for four other groups. Only with the symmetrical group did a symmetrical generalization gradient (with a peak at the TS) result. For the other groups, the peak was shifted from the TS toward the center of the test series. This finding, which Thomas and J ones called a "central tendency effect," has been replicated many times with different stimulus

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Stimulus generalization as a function of contextual stimuli.

Cited by 28 publications

References 1 publication

Stimulus Control and Generalization of Point‐loss Punishment With Humans

Stimulus Control and Generalization of Point‐loss Punishment With Humans

Temporal generalization and peak shift in humans

The central tendency effect in stimulus generalization: Effects of establishing a “preexperimental” frame of reference

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