The ability of preverbal infants to form and use ill-defined categories, to respond differentially to contrasting categories, and to use specific dimensions in learning these categories is examined in 20 infants 10 months of age. Results show that infants are not only capable of learning two ill-defined categories, but that they can do so with…

Visual preference and habituation paradigms were used to investigate the ability of three-month-olds to recognize the photographed face of the mother and to discriminate it from another face. Infants discriminated between the pictures of the mother and a stranger, both in the preference test and in the recognition test after habituation.…

Results indicated that, for all but one of eight autistic children, visual discriminations were acquired significantly faster, with fewer errors, when the S+ stimulus was faded first. These findings are related to the literature on the effects of stimulus novelty on selection and learning. (Author/RH)

Six- to 7-month-old infants were tested on their ability to discriminate among three speech sounds which differed on the basis of formant-transition duration, a major cue to distinctions among stop, semivowel, and diphthong classes. (Author/PHR)

The information load analysis of a discrimination-learning situation was studied by comparing speed of learning with a conventional reinforcement procedure and an inseparable reinforcer. Results showed more rapid learning by 4- to 6-year-olds with the inseparable reinforcer on earlier problems in a series and greater effect on more difficult…

Progressively delayed extra-stimulus prompts were used to help kindergarten children discriminate left-right mirror-image stimuli in four experiments. Results showed that most subjects rapidly learned to respond to the orientation prompts; delayed orientation prompting was always successful regardless of how the prompts were eliminated; and the…

Sixteen adolescents with mental retardation and 16 typical adolescents participated in a negative priming procedure in two experiments. Unlike previous studies, this study found that subjects exhibited inhibition under instructions to respond on the basis of stimulus identity in a manner similar to that of individuals without mental retardation.…

Behavioral responses of 3- to 4-day-old newborns to the odors of various human milk (HM) and formula milk (FM) were examined in paired-choice tests. When both stimuli were nonfamiliar, breast-fed, as well as bottle-fed, infants oriented their head and mouthed more vigorously to HM than to FM. When breast-fed infants were exposed to nonfamiliar HM…

This study demonstrates that non-human primates can categorize the direction of the pitch change of tones in a sequence. Two "Macaca fascicularis" were trained in a positive-reinforcement behavioral paradigm in which they listened to sequences of a variable number of different acoustic items. The training of discriminating pitch direction was…

Behavioral, neuropsychological, and brain imaging research points to a dedicated system for processing number that is shared across development and across species. This foundational Approximate Number System (ANS) operates over multiple modalities, forming representations of the number of objects, sounds, or events in a scene. This system is…

We explored the circumstances in which rats engage either declarative memory (and the hippocampus) or habit memory (and the dorsal striatum). Rats with damage to the hippocampus or dorsal striatum were given three different two-choice discrimination tasks (odor, object, and pattern). These tasks differed in the number of trials required for…

The conditions under which stimulus over-selectivity occurred were studied using a matching-to-sample procedure with non-autistic adults. A matching-to-sample discrimination learning task with a number of sample-comparison retention intervals was used. The results demonstrated that an increase in retention interval increased the degree of stimulus…

Thirty-six healthy participants received a discrimination learning task requiring the identification of a relevant stimulus dimension. After successful learning, the relevant dimension was shifted unannounced. All exemplars of the two dimensions presented after the shift were novel, implying a "total change" design. In three experimental…

Nonhuman animals, like humans, appear sensitive to the structure of the elements of sequences, perhaps even when the structure relates nonadjacent elements. In the present study, we examined the contribution of chunking, rule learning, and item memory when rats learned serial patterns composed of two interleaved subpatterns. In one group, the…