Temporal stability of the intrinsic motivation inventory

To examine the temporal stability of the Intrinsic Motivation Inventory a Greek version was administered to 144 undergraduate students after an endurance field test. The same procedure was repeated one week later. Factor analysis followed by varimax rotation showed that three factors (Perceived Competence, Interest/enjoyment, and Effort/importance) explained 65.26% of the total variance. Computed intraclass correlation coefficients (ICC) were .61 for the Perceived Competence subscale, .86 for the Interest/enjoyment, .60 for the Effort/importance, and .70 for the overall scale. The results, however, were modified when the sample was divided in two groups. The first represented small changes in perceived competence between the first and the second measurement, while the second one represented large changes between the two measurements. Recalculated intraclass correlation coefficients for individuals whose Perceived Competence score remained relatively stable yield a high value (.92), whereas individuals whose Perceived Competence changed yield an extremely low value (.60). It was concluded that the Intrinsic Motivation Inventory provides a temporally stable measure, given that perceived competence has not been markedly changed.     

Temporal generalization gradients following an interdimensional discrimination protocol

We investigated the effects of interdimensional discrimination training in the temporal generalization gradient. In a matching-to-sample task, pigeons learned to choose key S after a T–s houselight sample and key NS in the absence of the houselight sample. For one group of pigeons, T?=?20?s; for another, T?=?10?s. Subsequently, houselight duration was varied to obtain temporal generalization gradients. Results showed that (a) proportion S increased as houselight duration ranged from 0?s to T?s and then remained high for houselight durations longer than T; (b) the gradients were well described by negative-exponential functions; (c) these non-flat gradients were present from the beginning of testing, and; (d) the average gradients obtained with T?=?20?s and T?=?10?s overlapped when plotted in relative time. We conclude that temporal control does not require explicit discrimination training along the temporal dimension, and that temporal generalization gradients obtained with an interdimensional protocol show the scalar property of timing. We discuss how these findings challenge current models of timing.     

Tactile pattern perception by two fingers: Temporal interference and response competition

The identification of a spatial pattern (target) presented to one fingerpad may be interfered with by the presentation of a second pattern (nontarget) to either the same fingerpad or a second fingerpad. A portion of the interference appears to be due to masking and a portion to response competition. In the present study, vibrotactile spatial patterns were designed to extend over two fingerpads. Target and nontarget patterns were presented to the same two fingerpads with a temporal separation between the two patterns. The function relating target identification to the temporal separation between the target and nontarget was very similar to the functions obtained with one-finger patterns in temporal masking studies. Subsequent measurements showed that a substantial portion of the interference resulted from response competition. Pattern categorization was better when patterns were presented to two fingers on opposite hands than to two fingers on the same hand; however, there was more interference for patterns presented bilaterally than for patterns presented ipsilaterally. The results supported the conclusion that similar processes are involved in the perception of sequences of spatial patterns whether the patterns are presented to one or to two fingers.     

Comparison of response formats for Multidimensional Health Locus of Control Scales: six levels versus two levels

Two formats of the Multidimensional Health Locus of Control (MHLC) Scales were administered to 54 college students. Each subject completed the MHLC Scales in the standard 6-level response format (ranging from strongly disagree to strongly agree) and in a revised 2-level format (ranging from disagree to agree). Comparisons of internal consistency measures, principal components, and classification of subjects into groups indicate that the 2-level response format yields comparable data to those obtained with the 6-level format, particularly when classification of subjects is the goal.     

Consonant recognition with two levels of decision complexity

The perceptual tuning hypothesis can be expressed as a prediction that discrimination of a particular stimulus dimension will be enhanced if it is the only dimension requiring discrimination and not one of a set of dimensions in a multidimensional discrimination task. In previous tests of the tuning hypothesis, using speech material, the size of a message set has been manipulated as an indirect means of controlling the number of dimensions an observer is required to discriminate. In the present experiments the particular items appearing in a message set have been selected in order to control precisely the number of dimensions relevant to the discrimination task, and performance is estimated in terms of the discrimination of each relevant dimension. No evidence is found for a perceptual tuning effect even though it is argued that the conditions of the present experiment represent those most favourable for its elicitation.     

Indications for two attentional gradients in endogenous visual-spatial attention

Four experiments were designed to investigate the meridian effect on attentional orienting (characterized by a larger cost when the cue and target fall in different visual fields relative to when they fall in the same fields) when employing an endogenous cue. In Experiment 1 a circular display of eight boxes was employed and no meridian effect was found. In Experiment 2 three displays were compared: Semicircular, vertical, and horizontal. No meridian effect was found in the semicircular display. However, in the two linear displays (vertical, horizontal) there was a significant meridian effect. Experiments 3 and 4 were designed to investigate an attentional gradient hypothesis. In all experiments a distance effect was found. Nevertheless, the distance effect was not directly related to the actual distance between the target positions. The results suggest the existence of two attentional gradients that develop simultaneously in the visual field: an excitation gradient centred at the cued location (the strongest excitation) and an inhibition gradient, centred at the fixation point (the strongest inhibition).     

Conditioned reinforcement and response strength

Stimuli associated with primary reinforcers appear themselves to acquire the capacity to strengthen behavior. This paper reviews research on the strengthening effects of conditioned reinforcers within the context of contemporary quantitative choice theories and behavioral momentum theory. Based partially on the finding that variations in parameters of conditioned reinforcement appear not to affect response strength as measured by resistance to change, long-standing assertions that conditioned reinforcers do not strengthen behavior in a reinforcement-like fashion are considered. A signposts or means-to-an-end account is explored and appears to provide a plausible alternative interpretation of the effects of stimuli associated with primary reinforcers. Related suggestions that primary reinforcers also might not have their effects via a strengthening process are explored and found to be worthy of serious consideration.     

Auditory generalization gradients for response latency in the monkey

Two monkeys were trained to press and hold a response key in the presence of a light and to release it at the onset of a pure tone. Initially, all responses with latencies shorter than 1 sec were reinforced without regard to the frequency of the pure tone, and the intensity of the pure tone that resulted in equal latencies at each frequency was determined. The second stage of the experiment consisted of discrimination training, during which releases to one pure-tone frequency (positive stimulus) were reinforced and releases to a second frequency (negative stimulus) were extinguished. Median latencies to the negative stimulus slowly increased as did the variability of the latency distribution for the negative stimulus. There was no evidence of a concurrent decrease in latencies to the positive stimulus indicative of behavioral contrast. The third part of the experiment consisted of determining maintained generalization gradients by increasing the number of nonreinforcement stimuli. The gradients that eventually resulted showed approximately equal latencies to all frequencies of the negative stimulus and shorter latencies to the positive stimulus frequency.     

Dissociation of value and response strength

Four pigeons were exposed to multiple schedules and later to concurrent-chains schedules, with terminal links that had previously been multiple-schedule components. For 2 birds, the terminal-link schedules arranged an inverse relationship between response rate and reinforcement rate; for the other 2 birds a direct corresponding relationship was arranged. Those response rates were further modified by differentially reinforcing either longer or shorter interresponse times, relative to the current means. Although the birds' initial-link responses indicated preferences for terminal links with higher rates of reinforcement, in half the cases the birds responded during the terminal links in such a way as to produce lower rates of reinforcement, rates their initial-link behavior indicated they did not prefer. That outcome is inconsistent with maximization theory, but consistent with a strengthening analysis of behavior on single-key schedules.