The easy to hard effect and perceptual learning in flavor aversion conditioning

In experiments on the easy to hard effect, pretraining on an easy discrimination results in better performance on a harder version of the discrimination than pretraining on the hard discrimination itself. In addition, some theories posit that unreinforccd preexposure to the easy discrimination should be as effective as differentially reinforced easy pretraining in producing the easy to hard effect. Two experiments on flavor aversion conditioning in rats demonstrated the basic easy to hard effect. However, in neither experiment was easy preexposure more effective than hard preexposure in enhancing learning of the hard discrimination. Indeed, in Experiment 2, rats preexposed to an easy discrimination learned the hard discrimination significantly more slowly than those preexposed to the hard discrimination itself.     

Factors affecting hypothesis testing in kindergarten children

In a previous experiment, the authors demonstrated that kindergarten and first-grade children can be trained to test hypotheses sequentially within the context of a discrimination learning task. The present experiment is concerned with delineating various aspects of the pretraining that contribute to the improved hypothesis-testing strategies of kindergarten children (mean CA = 71.6 months). It was found that children who have learned to anticipate an invariant cue-reward relation in such tasks manifest improved hypothesis-testing behavior, as well as improved discrimination performance, whereas children who have been trained to identify and name the various stimulus components of the discriminanda do not perform better than those without such training. It was also found that children who have had practice in shifting from an irrelevant to a relevant dimension perform better than those who have not had such experience. Moreover, children who have been given explicit instruction and training in the use of win-stay and lose-shift rules, as well as in the use of valid hypotheses, manifest strategies superior to those without such training. Finally, extensive pretraining over two sessions, administered on separate days, resulted in a marked reduction in the proportion of children who were dimensionally fixated while solving discrimination problems with two genuine dimensions.     

Stimulus interaction and transfer of discrimination in children

Two discrimination learning experiments on third- and fourth-grade children are reported. In Expt I, Ss received either simultaneous or successive pretraining followed by simultaneous or successive transfer tasks in which an irrelevant dimension was varied either between or within settings. With the incorporation of a response-produced cues proposal, a modified version of the Hull-Spence theory (C. C. Spiker, Psychological Review, 1970, 77, 496–515) accounted for 81.2% of the variance of the group means and provided a satisfactory method of both quantifying and manipulating the mechanisms of associative transfer, even when the dimensions of pretraining and transfer differed. Because simultaneously pretrained Ss performed more as was expected than did successively pretrained Ss, it was hypothesized that Ss have an extraexperimental tendency to respond to dimensions varying within settings. This hypothesis was supported by the results of Expt II, in which an extensive shaping procedure was used for simultaneous, successive or control pretraining tasks followed by a successive transfer task in which the arrangement of two irrelevant dimensions was manipulated.     

Incidental learning,attention, and curiosity in squirrel monkeys calorie deprived as infants

The long-term effects of infantile malnutrition on information processing were studied in squirrel monkeys. From 2 through 8 weeks of age, four low-calorie infants were fed reduced amounts of a high protein diet, limiting their mean body weight gain to 23% of that of four well-fed controls, with all of this gain occurring during the first 2 weeks on the low-calorie diet. Thereafter, both groups received the standard diet ad libitum. At 68 weeks of age, incidental learning was tested by introducing shape cues that were redundant to the solution of a previously learned, two-choice, color discrimination. Removal of the color cues showed that the low-calorie monkeys had learned significantly less about the shape cues than had the controls. The basis for this incidental learning failure was then examined with an embedded-figures dicrimination, to measure attentional ability, and a novel stimulus substitution task, to measure curiosity. The groups did not differ in detecting embedded figures, but the low-calorie monkeys were significantly less likely than controls to select or handle novel stimuli that had been substituted for previously learned discriminative cues. It was concluded that undernutrition in infancy may induce a long-term strategy of only learning information which leads to an immediate reward, while suppressing the acquisition of information due to intrinsic curiosity.     

Generation difficulty and memory for source

The role of the word predictability from sentence context for reality monitoring and external source monitoring was examined in two experiments. In a reality-monitoring task, discrimination of an internal source was better in the hard than in the easy condition. It is probable that extra cognitive operations engaged during word generation in the hard condition were effective cues for reality-monitoring judgements. In contrast, in an external source-monitoring task (recognition memory of item's colour), the hard condition resulted in worse source memory for generated words than did the easy condition. This result is consistent both with an item-context trade-off hypothesis and a processing hypothesis. Greater effort involved at the time of generation might limit resources available for encoding of an external source. It is also possible that for generated words, the hard condition promoted conceptual processing instead of perceptual processing; therefore the item's colour was not effectively encoded.     

The generality of transfer: Effects of age and similarity of training and transfer tasks

Two experiments were conducted investigating the extent to which transfer of training would take place. The Ss were trained to attend to a particular dimension (color or form) of a set of stimuli and were then presented with a transfer problem. For half the Ss the transfer problem was an intradimensional (ID) shift, and for the remaining half an extradimensional (ED) shift, with the ID-ED difference then being used as an index of the magnitude of transfer. Previous data had indicated that preschool and kindergarten children did not effectively transfer learned attention responses from one task to another if the formats of the two problems were different. Experiment I investigated the hypothesis that older children would show broader patterns of transfer. However, the patterns obtained with second and fifth graders were extremely similar to those obtained with younger children. In Exp. II, it was found that transfer did take place across different task formats if the stimuli remained the same from training to transfer. The data were discussed in terms of the role of contextual cues, or context markers, in the origical acquisition of information and the subsequent transfer (use) of that information.     

Incidental cue learning in rats

Continuity theories of discrimination learning appear to say that animals learn equally about all cues impinging upon their receptors; noncontinuity theories that they learn about only one cue at a time. Experiment I showed that neither of these positions is correct: rats trained to attend to one cue learned less about a subsequently introduced incidental cue than rats given no such pretraining; but attention to one cue did not totally prevent learning about the other. A second experiment established that if rats are trained with one cue, and a second cue is then also made relevant, the amount learned about this second cue varies directly with (a) the abruptness with which it is introduced, and (b) the difficulty of the original discrimination.     

Blocking and overshadowing in two species of fish.

In Experiment 1, a mixed blocking-overshadowing effect of color on an auditory discrimination was demonstrated in goldfish. In Experiment 2 (with lines differing in color and angle), blocking of angle by color and of color by angle was demonstrated in goldfish, In Experiment 3 (again with lines differing in color and angle), overshadowing of angle by color was demonstrated in carp, but the same animals (like goldfish in a previous study) failed to show greater intradimensional than extradimensional transfer. These results are consistent with the hypothesis that blocking and overshadowing are general phenomena of vertebrate learning. They suggest also that the processes responsible for blocking and overshadowing are different from those which produce the dimensional transfer effect.     

Teaching autistic children to use extra-stimulus prompts

Autistic children often do not transfer from extra-stimulus prompts, and thus do not utilize a frequent learning aid. It has been hypothesized that this is due to stimulus overselectivity; a failure to respond to simultaneous multiple cues. This study was designed to determine if autistic children who initially respond only to single cues can be taught a set to respond to two cues and subsequently utilize an extra-stimulus (pointing) prompt. Four autistic children were pretested to determine if they could learn a complex visual discrimination by either trial and error or an extra-stimulus prompt fading procedure. Since they did not, the children were then taught to respond to two cues through a multiple-cue training procedure and subsequently tested to determine if they could now utilize a pointing prompt. Results indicated that while all four children initially did not transfer from an extra-stimulus (pointing) prompt, they did so subsequent to multiple-cue training. The results are discussed in terms of implications for treatment (remediating overselectivity) and in relation to normal child development.     

Generation difficulty and memory for source

The role of the word predictability from sentence context for reality monitoring and external source monitoring was examined in two experiments. In a reality-monitoring task, discrimination of an internal source was better in the hard than in the easy condition. It is probable that extra cognitive operations engaged during word generation in the hard condition were effective cues for reality-monitoring judgements. In contrast, in an external source-monitoring task (recognition memory of item's colour), the hard condition resulted in worse source memory for generated words than did the easy condition. This result is consistent both with an item–context trade-off hypothesis and a processing hypothesis. Greater effort involved at the time of generation might limit resources available for encoding of an external source. It is also possible that for generated words, the hard condition promoted conceptual processing instead of perceptual processing; therefore the item's colour was not effectively encoded.     

Attention to components or compounds as a factor in discrimination transfer performance.

Prior to being tested with standard reversal or extradimensional (ED) shift procedures, two groups of mentally retarded subjects (MA: 4 to years) were pretrained using two different methods. The Component group received two problems which could be solved easily only by attending to the form components. The Compound group was trained on two problems requiring attention to compound color-form cues. It was assumed that the two solution modes would carry over to the third problem, which was for both groups a standard form discrimination with color variable and irrelevant within settings. The fourth problem was either an ED shift or a reversal. The Component group learned reversal faster than ED shift whereas the opposite was true for the Compound group. Subproblem analyses of ED shift performance showed dependent settings for the Component group and independent settings for the Compound group. Results are consistent with the view that compound and component solutions of discriminative problems are achieved by attention to the abstract dimensions of compounds or components and that attention to either of these dimensions can be trained at higher or lower developmental levels even though the salience of the compound dimension may be initially greater for lower level subjects.     

Teaching autistic children to respond to simultaneous multiple cues

A number of studies have shown that autistic children tend to learn new discriminations by responding to only a restricted number of available cues and that this may be responsible for some of their abnormal behavior. Therefore, this investigation assessed the feasibility of teaching autistic children to respond to multiple cues. The results showed that four autistic children could learn a conditional discrimination requiring them to discriminate a multiple-cue complex from each of its two component cues. However, the autistic children did not learn this discrimination in the same manner as normal children. In the early trials, the autistics responded at a higher level to one of the two component cues. Only after many trials did the autistics respond equally on the basis of both component cues. The results of an initial attempt to teach a general set to respond to multiple cues showed that, when an autistic child was taught a series of successive conditional discriminations, the child eventually learned a set to approach new discriminations by responding equally on the basis of both component cues. The results are discussed in terms of understanding and treating autistic children's abnormal development.     

Stimulus control and delayed reinforcement

Pigeons were tested for generalization along the line-orientation dimension, after being trained on various two-component multiple schedules. The first component contained either a variable-interval 1-min schedule of immediate reinforcement or an extinction schedule and was associated with a plain white key (S1). The second component contained a variable-interval 1-min schedule of delayed reinforcement and was associated with a black line on a white background (S2). The major results showed that (a) decremental gradients were obtained around the stimulus associated with the delayed reinforcement component when S1 was associated with extinction, but that incremental gradients were obtained when S1 was associated with immediate reinforcement, (b) the subjects' pretraining did not affect the generalization gradients if sufficient training on the terminal multiple schedule was provided, and (c) changing the S1 schedule from immediate reinforcement to extinction produced behavioral contrast if reinforcement was delayed for 10 sec during S2, but not if it was delayed for 20 sec.     

Early discrimination among small object collections

Two studies are presented which examine the young child's ability to discriminate between two small object collections on the basis of numerosity and to maintain that discrimination across changes in number-related cues. A transfer procedure and counting tasks were also included. In Study 1, 2-, 3-, and 4-year-olds were reinforced for choosing either a two- or three-item array when length-density cues were manipulated across two training phases of 20 trials each. Training was followed by a transfer task in which one- and four-item arrays were displayed. Most 2-year-olds were able to learn the discrimination while at the same time displaying little quantitative ability. Further, their transfer responses were transpositional in nature. In Study 2, 2-year-olds were given a similar discrimination task in which numerosity was contrasted simultaneously with length-density and area-brightness cues. Again, most children learned the discrimination and transferred that learning on the basis of relational cues.     

The effect of the temporal locus of the introtact probe on the hypothesis-testing strategies of kindergarten children

The hypothesis-testing behavior of kindergarten children in discrimination learning was studied in a factorial design with two temporal placements of introtact probes (pretrial and posttrial) and two types of pretraining (unidimensional and multidimensional). Pretrial probes consisting of a request for the child's current hypothesis were administered in a conventional manner at the beginning of each trial with the stimuli in view and prior to the choice response. Posttrial probes were administered also with the stimuli in view, but after the choice response had occurred and feedback information had been provided. Learning-to-learn experience in solving three pretraining problems was given either with unidimensional simultaneous problems or with more complex multidimensional problems like the criterion tasks. The results indicated that posttrial probes produced superior local consistency, win-stay, and lose-shift probabilities, relative to pretrial probes, for both types of pretraining. Posttrial probes, however, facilitated learning and the testing of valid hypotheses only for multidimensional pretraining. These results are consistent with the hypothesis that posttrial probes constrain the child to be locally consistent and therefore improve short-term efficiency in hypothesis testing under both pretraining conditions. However, posttrial probes produce an improvement in long-term efficiency, and therefore in learning, only when other components of a successful strategy are acquired as in multidimensional pretraining.     

Partial reinforcement and breadth of learning

Two experiments on partial reinforcement were undertaken to test predictions made by a two process model of discrimination learning. In the first experiment rats were trained on a discrimination involving two relevant cues: one group (C) was trained on a 100: o schedule, the other (P) on a 50:0 schedule. Both groups were then given transfer tests with the two cues presented individually; finally all animals were extinguished on the original training stimuli and on the single cue stimuli. During extinction there was a negative correlation between the number of correct responses made by individual subjects of Group C to each single cue; whereas the correlation was positive for subjects of Group P. The second experiment employed basically the same design, but subjects were trained with seven relevant cues. The results of transfer tests showed that subjects of Group P learned to attach the correct response to many more cues than subjects of Group C. This suggests that the breadth of learning is greater under partial than under consistent reinforcement. The results were predicted by the model of discrimination learning under test.     

The intermediate-hue transposition of children after same-different and seriation pretraining

The intermediate-hue transposition of first- and second-grade children was investigated in two experiments. In Expt. 1, it was found that seriation pretraining increased the amount of far transposition regardless of whether or not the same hues were used in pretraining and subsequent tasks. In Expt. 2, seriation pretraining produced more far transposition than did same-different pretaining and a no-pretraining control. The latter two conditions were not significantly different. Three assumptions about the effects of perceptual pretraining on subsequent transposition were described and related to the data.     

The problem-solving strategies of kindergarten and first-grade children during discrimination learning

Kindergarten and first-grade children (6 and 7 years of age, respectively) were given specially designed discrimination tasks with introtact probes preceding each trial. One group (CON) was given the criterion task without prior training. A second group (LTL) received three pretraining tasks of the same type as the criterion task. A third group (HYP) received the same pretraining tasks, but with explicit instructions designed to teach a simple hypothesis-testing strategy. Several indices, designed to reflect the use of win-stay and lose-shift rules, as well as memory for disconfirmed hypotheses, were computed from the protocols of the criterion task. The indices for Group CON suggested that most of these children were using a guessing strategy that involved quite frequent changes in hypotheses. Moreover, many of these children restricted their hypotheses to the irrelevant cues. The indices for Group LTL revealed a spontaneous use of the hypothesis-testing strategy by nearly half of the children. The results for Group HYP indicated that over four-fifths of these children became highly efficient in the use of the problem-solving strategy.