Assessment of vocational maturity

A comparison is made between the Vocational Development Inventory and the Readiness for Career Planning scale when both were administered to the same sample. An analysis of covariance, with intelligence controlled for, indicated that both instruments show an over-all progression in vocational maturity at different grade levels, as well as differences between socioeconomic groups. A correlational matrix found vocational maturity scores from the two instruments to be significantly related.     

A sufficient condition for conditional expectation to be monotonically related to distribution parameters

In this paper we give a sufficient condition for conditional expectation to be a monotonic function of a parameter of the joint probability distribution. A second sufficient condition is given for the case where varying the parameter of the joint distribution leaves the shape of that distribution unchanged. Finally, an application of the condition is illustrated on the counter models for choice reaction time of LaBerge (1962) and Nickerson (1969).     

Additivity of risk in portfolios

A collection of gambles constituting a portfolio may itself be represented as a single gamble played once. A portfolio may be constructed by requiring each component gamble to be played once, and there is a theory of additive risk which requires that the perceived risk of the portfolio be an additive function of the perceived riskiness of the component gambles. Alternatively, a portfolio may be constructed as a probability mixture of the component gambles, and there is a theory of expected risk which requires that the perceived risk of the portfolio be the average of the riskiness of the component gambles. Existing evidence suggests that both of these theories cannot be true. A test of additivity of portfolios under both kinds of composition functions was made under two forms of display, the components displayed separately and fused as a single gamble. This experiment supports expected risk and rejects additive risk, especially under fused display.     

Comments on “markovian processes with identifiable states: General considerations and applications to all-or-none learning”

When knowledge of the response sequence permits one to specify the sequence of theoretical states that occurred, we propose to say that the theory has observable states. Our earlier usage of identifiable conflicts with established usage in econometrics. We also present a revised definition of implication between theories that avoids a technical flaw in the earlier definition, and we correct a mistake in an example in our earlier paper.     

Some effects of discriminative training with equated frequency of reinforcement

Pigeons were exposed to a multiple schedule which provided equally frequent reinforcement in the presence of two stimuli but which produced markedly different rates of key-pecking. Generalization gradients were displaced away from the stimulus associated with the lower rate of key-pecking. Another group of pigeons had similar training, except that a low rate of key-pecking was established in a stimulus with a much higher frequency of food reinforcement. In this case, the generalization gradients were not affected by the training on the schedule producing a low response rate.     

Perception of sequentially presented tactile point stimuli

Either two or three brief (10 msec) airjet stimuli were sequentially presented to any of the 24 interjoint regions of the fingers (thumbs excluded). The stimulus onset interval (SOI) ranged from zero (simultaneous presentation) through 200 msec. The S’s task in one part of the experiment was to report the positions stimulated in the order that the stimuli were presented; in a second part it was to rate the apparent motion produced by the stimulus sequence. While the ability of Ss to spatially localize the stimuli was a constant independent of SOI, their ability to temporally order the stimuli depended strongly on SOI. With two stimuli, these sequential errors decayed exponentially with SOI with a time constant of 26 msec. With three stimuli, however, both the sequential errors and equivalent temporal Urnen were more than twice as large as with two stimuli, indicating that the three-stimulus task is considerably more difficult than the two, and that the same simple temporal resolution model does not explain both cases. A model with a constant rate of information uptake, however, can explain both of these cases.     

A convective thermal controller for behavioral experiments

The Convective Thermal Controller (CTC) is designed to provide rapid and precise control of a thermal stimulus for application to behavioral experiments with small animals. Subjects are bathed in one of two continuously recirculating air systems; two valves determine which of the systems play on S. When the systems are stabilized at different temperatures, actuation of the valves can produce an abrupt and stable temperature change in .3 sec. Behavioral observations indicate that escape learning occurs readily; latency decreases monotonically with drive intensity and increases monotonically with reinforcement duration.     

Recognition and recall by children and adults as a function of variations in memory encoding instructions

In four experiments Ss were instructed to learn a set of 40 words by producing implicit associative responses to each item (association instructions), by repeating items over and over (repetition instruction), or by using their own devices (neutral instructions). Experiment I showed that recognition memory (RM) accuracy was greatest under association instructions for adults and children and least under repetition instructions for children. The implications of these results for a frequency theory analysis for RM were discussed. Experiments II, III, and IV examined free recall (FR) as a function of encoding instructions at short (1 min) and long (either 90 min or 24 h) retention intervals. FR was worst under repetition instructions, with little overall difference between the association and neutral conditions. However, in Experiments III and IV, using school children, the neutral condition exceeded the others in FR after 90 min but not after 1 min.