The form of analog size information in memory

The information used to choose the larger of two objects from memory was investigated in two experiments that compared the effects of a number of variables on the performance of subjects who either were instructed to use imagery in the comparison task or were not so instructed. Subjects instructed to use imagery could perform the task more quickly if they prepared themselves with an image of one of the objects at its normal size, rather than with an image that was abnormally big or small, or no image at all. Such subjects were also subject to substantial selective interference when asked to simultaneously maintain irrelevant images of digits. In contrast, when subjects were not specifically instructed to use imagery to reach their decisions, an initial image at normal size did not produce significantly faster decisions than no image, or a large or small image congruent with the correct decision. The selective interference created by simultaneously imaging digits was reduced for subjects not told to base their size comparisons on imagery. The difficulty of the size discrimination did not interact significantly with any other variable. The results suggest that subjects, unless specifically instructed to use imagery, can compare the size of objects in memory using information more abstract than visual imagery.     

Effects of differential reinforcement and task difficulty on preschoolers' compliance with teacher instructions

Preschool children in day schools were given instructions to complete certain tasks. Four tasks were given of two types and two levels of difficulty. In each condition compliance with at most one instruction (one task) was reinforced. In two similar experiments, with six children, general results were: compliance with easy tasks was maintained without reinforcement when any task compliance was reinforced; compliance for hard tasks remained high only when that specific task was reinforced. Thus, generalization of compliance with instructions varied with task difficulty. The setting and procedure for both studies were designed to reduce possible coercive features of laboratory studies of generalized performance. Results show generalized performance can occur under naturalistic conditions. The effect of effort, as a response characteristic affecting generalized performance, is discussed.     

Avoidance extinction in goldfish

Independent groups of goldfish trained to avoid shock in a shuttlebox situation were presented with several extinction procedures in which the relationships between the conditioned stimulus and shock were altered and/or response contingencies removed. Random shock presentations, equivalent to the number of shocks received during avoidance acquisition, resulted in response decrements similar to those obtained when the conditioned stimulus was presented alone. Pairing the conditioned stimulus with shock on every trial, however, served to maintain response levels. When response-contingent punishment was superimposed upon these Pavlovian pairings, performance was facilitated slightly although punishment alone resulted in somewhat faster response reduction than that produced by exposure only to the conditioned stimulus. Extinction of avoidance responding produced by exposure to the conditioned stimulus alone was dependent on the total duration of exposure and independent of both number of stimulus onsets and response prevention. These experiments demonstrated that, in general, the procedures used to reduce avoidance responding in rats were equally effective for goldfish, with one exception: the introduction of a Pavlovian contingency following avoidance acquisition, making the previously avoidable shock unavoidable, maintained response probabilities near previously established levels.     

Listening to speech while retaining music: What happens to the right-ear advantage?

On each trial, subjects were played a dichotic pair of syllables differing in the consonant (/ba/, /da/, /ga/) or in the vowel (/ba/, /b?/, /bi/). The pair of syllables was preceded by a melody, or a sentence, and followed by the same or a different melody, or sentence. Subjects either had to retain the first piece of additional material or were free to ignore it. The different combinations of phonemic contrast, additional material, and instruction concerning the additional material were used in different sessions. In each case, the main task of the subjects was to respond to the presence or the absence of the target /ba/ on the ear previously indicated. There was no effect of context on relative ear accuracy, but the right-ear advantage observed for consonants in response latency when subjects retained a sentence gave way to a small nonsignificant left-ear advantage when subjects retained a melody. Right-ear advantage in response latencies was also observed for vowels in the verbal context, but the contextual effect, although in the same direction as for consonants, was very slight. The implications of contextual effects for a theory of the determinants of the auditory laterality effects are discussed.     

A comparison of attentional and control shift models of the performance of concurrent tasks

A concurrent verbal task was superimposed upon the performance of a practiced bimanual motor skill by right-handed Ss. Addition of the verbal task did not increase the total number of errors; however, a significant interaction between hands and conditions was observed. The right hand made significantly more errors under the verbal condition, while the left hand made non-significantly fewer errors under that condition. These findings were interpreted as supporting an attentional model rather than a model which proposes that addition of the verbal task causes control of the right hand to shift to the non-verbal right hemisphere.     

Establishing discriminative stimulus control within generalized oddity performance,without reinforcement

In two oddity learning studies with children, subjects were reinforced for oddity (or nonoddity) responding on line-tilt or dot numerosity problems. Interposed form and color problems were not reinforced. No instructions to make oddity choices were given. In Experiment I it was found that reinforcement for oddity or nonoddity responding on tilt and numerosity problems produced the corresponding tendency toward oddity or nonoddity performance on these problems and also on the nonreinforced form and color problems. These results show a generalized oddity phenomenon similar to generalized imitation. In Experiment II a third type of nonreinforced problem was presented in this same format: compound stimuli permitting either a color or a form solution. It was found that immediate prior training with nonreinforced form problems, interpolated among the reinforced tilt and numerosity problems, led to form-oddity choices in the compound problems. Similarily, color pretraining produced color-oddity choices. These results show that selective discriminative stimulus control can be obtained in oddity learning, without reinforcement for choices on either of the two dimensions involved.