Stimulus change and complexity in exploratory behavior

It has recently been proposed (Fowler, 1967, 1971) that the incentive value of novelty can be defined in terms of stimulus change. An experiment is reported which examines the relationship between changes in complexity and the consequent exploratory behavior. Following extended exposure to a midcomplexity stimulus, rats were allowed to choose between a stimulus change and the now familiar midcomplexity stimulus. For some Ss the change was to a stimulus of higher complexity, and for others the change was to a lower complexity stimulus. The results suggest that physical stimulus changes to a stimulus of greater complexity is a more effective novel stimulus than physical stimulus changes to lesser complexity, although both changes may function as incentives.     

Compulsive-like behavior in individuals with Down syndrome: its relation to mental age level, adaptive and maladaptive behavior

This study examined the nature of repetitive, ritualistic, and compulsive-like behaviors in 50 typically developing children and 50 individuals with Down syndrome (DS), matched on mental age (MA; M = 59.72 months). Parents reported on their children's compulsive-like behaviors-including ritualistic habits-and perfectionistic behaviors, as well as their children's adaptive and maladaptive behaviors. Results indicated that children with DS show similar MA-related changes in compulsive-like behaviors compared to the MA-matched comparison group. Younger children (both typical and DS) exhibited significantly more compulsive-like behaviors than older children. In general, children with and without DS did not differ from each other in terms of the number of compulsive-like behaviors they engaged in, although participants with DS engaged in more frequent, more intense repetitive behaviors. Compulsive-like behaviors were differentially related to adaptive and maladaptive behaviors across the MA and mental retardation groups. The results extend the "similar sequence" model of development to the construct of compulsive-like behaviors, and also suggest that some repetitive behaviors may be among the behavioral phenotype of individuals with DS.     

The organization and temporal properties of appetitive behavior in rats

In the presence and absence of an externalinterfood clock stimulus (a sequence of flashing lights), rats showed a multimodal behavior pattern during successive quarters of interfood intervals (IFI) ranging from 12 to 192 sec. Responses near the feeder peaked before and just after food presentations, whereas locomotion remote from the feeder peaked toward the middle of the IFI. The temporal patterns of nosing in the feeder and remote locomotion were scalar (the time at which a response peaked in the IFI was proportional to the IFI length), whereas the patterns of postfood feeder-directed behavior, rearing, and pawgrooming were time bound (peaking at a fixed time after food, regardless of IFI length). Responses varied in their control by the external clock stimulus. During the last half of the IFI, rats nosed in the feeder more with an external clock, but only at intermediate IFIs. During the first quarter of the IFI, rats pawgroomed more with an external clock, but only at the longest IFI. The general sequence of responses during the interfood clock was consistent with the view that food delivery engages an organized sequence of search states that are expressed through a variety of responses.     

Experiential aspects of exploratory behavior in rats

Twenty-four male rats were reared under three feeding conditions. These conditions manipulated the number and variety of exploratory behaviors required to obtain diets of powdered food and water in feeding boxes. One group performed minimal exploratory responses to obtain their diets. Another group shuttled between two feeding stations, thereby executing several exploratory components, primarily locomotor. The third group performed a considerable number and variety of exploratory components in search of their diets, located unsystematically throughout the feeding box. Adult testing occurred without food and water in an apparatus resembling the feeding boxes. The results showed that exploratory behavior was affected by feeding conditions, enhanced with increased dietary deprivation, and reduced across both trials and within-trial intervals. These results indicate that the particular exploratory behavior measured must be selected by reference to the subjects’ prior experience.     

Inhibition of exploratory behavior in the rat by handling

The effect of tail-handling on exploratory behavior of the rat, measured as step-through latency in a well-lighted, two-box apparatus, was investigated. Male adult Wistar rats, aged 60 days, were employed in all three experiments. Experiment 1, in which the subjects were handled at different times after entering the goal chamber (0, 10, 30, 60, 300, and 600 sec), showed that immediate handling, relative to detention in the goal chamber (delay of handling) had an inhibitory effect on exploration. Experiment 2 showed that groups handled immediately after entering the goal chamber but then detained there for different durations all showed the same progressive inhibition of exploration. Experiment 3 showed that the inhibition of exploration (very long step-through latencies) due to tail-handling immediately after entering the goal chamber could be significantly decreased by further trials in which handling was delayed for a sufficient duration (30 sec or more). Handling is discussed as a stimulus that is aversive enough to elicit conditioned passive-avoidance responses (inhibition of exploratory behavior), although it is subject to rapid extinction.     

The neuropsychology of Down syndrome: evidence for hippocampal dysfunction

This study tested prefrontal and hippocampal functions in a sample of 28 school-aged (M = 14.7 years, SD = 2.7) individuals with Down syndrome (DS) compared with 28 (M = 4.9 years, SD = .75) typically developing children individually matched on mental age (MA). Both neuropsychological domains were tested with multiple behavioral measures. Benchmark measures of verbal and spatial function demonstrated that this DS sample was similar to others in the literature. The main finding was a significant Group x Domain interaction effect indicating differential hippocampal dysfunction in the group with DS. However, there was a moderate partial correlation (r = .54, controlling for chronological age) between hippocampal and prefrontal composite scores in the DS group, and both composites contributed unique variance to the prediction of MA and adaptive behavior in that group. In sum, these results indicate a particular weakness in hippocampal functions in DS in the context of overall cognitive dysfunction. It is interesting that these results are similar to what has been found in a mouse model of DS. Such a model will make it easier to understand the neurobiological mechanisms that lead to the development of hippocampal dysfunction in DS.     

Nonverbal communication skills in Down syndrome children

The goal of this research was to examine the nonverbal communication competence of 18-48-month-old Down syndrome children. The results indicated that Downs children displayed strengths and weaknesses in nonverbal communication skills. Relative to MA matched normal children, they displayed a significant strength in nonverbal social interaction skills. However, they also displayed a significant deficit in nonverbal requests for objects or assistance with objects compared to normals. This pattern of strength and weakness in nonverbal skills appeared to be specific to Down syndrome since this pattern was not displayed by a comparison sample of non-Downs mentally retarded children. Nonverbal object-requesting skill was also significantly associated with a measure of expressive language in the Downs sample. This relation was notable because the Downs children also displayed a deficit in expressive language. Thus, the results of this study suggest that a deficit in expressive language is associated with a deficit in earlier-developing nonverbal requesting skill among Down syndrome children.     

Literacy skills in children and adolescents with Down syndrome

Research has found that many children andadolescents with Down syndrome acquire somelevel of reading ability. Studies to date havedocumented that cognition, language, andphonological awareness contribute tovariability observed in performance onconventional literacy measures for thispopulation, although the extent of relativecontributions varies among studies. Less isknown about the relationship of early literacyskills to conventional reading, or howrelationships among variables that supportliteracy acquisition are similar or differentfrom those observed in typically developingchildren. In this project, cognition,language, early literacy, phonologicalawareness and reading skills were examined in agroup of children and adolescents with Downsyndrome (aged 5;06 to 17;03) and a group oftypically developing children (aged 3;06 to5;03) matched for nonverbal cognition. Resultsrevealed broad variability in performance onearly literacy and reading measures in personswith Down syndrome. Comparisons with mental age-matchedchildren indicated differences in the relativecontribution of language and cognition toreading ability, with language being a strongerpredictor in the group with Down syndrome.     

Nonword reading and other reading-related skills in Down syndrome

The performance of children and young adults with Down syndrome (DS) on reading subskills and nonword reading was investigated. The performance of the participants with DS (N = 42) was compared to that of typically developing (N = 36) peers matched on fluid intelligence abilities. The study accounted for the different depths in orthography presented by the two languages. The independent samples t-test, Mann–Whitney U-test, ANCOVA and correlation analysis were used to analyse the data. This study identified that the participants with DS had several strengths, such as nonword reading, visual discrimination (VD) and phonological awareness. Verbal short-term memory, visual perceptual processing skills other than VD and rhyming skills were identified as weaker in DS compared with the control group. Results call for educators to expose readers with DS to a phonological approach to reading while accommodating difficulties in VSTM.     

Determinants of withdrawal behavior: An exploratory study

Research on college persistence has typically classified nonreturnees as dropouts. Recently, this practice has been criticized by Tinto (1987) who argues that such a practice merges together different types of withdrawal behavior whose determinants may vary as a function of the particular departure behavior under consideration. This paper empirically examines whether the determinants of decisions to withdraw from the institution are similar to those affecting decisions to transfer to other institutions of higher education for the 1984 entering freshman class at a large southern institution. Results provide support for Tinto's proposition of differentiating between different types of voluntary withdrawal behavior. While institutional commitment, academic performance, finance attitudes, and student perceptions of faculty concern for student development and teaching discriminated between persisters and dropouts, only final institutional commitment and final goal commitment discriminated between persisters and transfers.An earlier version of this paper was presented before the 1990 American Educational Research Association annual meeting.     

The motor core of speech: a comparison of serial organization patterns in infants and languages

Comparison of serial organization of infant babbling and early speech with that of 10 languages reveals four movement-related design features reflecting a deep evolutionary heritage: (1) the cyclical consonant-vowel alternation underlying the syllable, a "Frame" for speech consisting of mandibular oscillation, possibly evolving from ingestive cyclicities (e.g., chewing) via visuofacial communicative cyclicities (e.g., lipsmacks); (2) three intracyclical consonant-vowel co-occurrence preferences reflecting basic biomechanical constraints-coronal consonants-front vowels, dorsal consonants-back vowels, and labial consonants-central vowels; (3) a developmental progression from above-chance to below-chance levels of intercyclical consonant repetition; (4) an ease-related labial consonant-vowel-coronal consonant sequence preference for word initiation. These design features presumably result from self-organizational responses to selection pressures, primarily determined by motor factors. No explanation for these design features is available from Universal Grammar, and, except for feature 3, perceptual-motor learning seems to have only a limited causal role in acquisition of any design feature.     

Effects of maze geometry and experience on exploratory behavior in the rat

Rats were exposed twice in a rotated sequence to a series of six mazes, consisting of hexagonal alleys, balanced for different alley length and structural complexity. Locomotor activity increased with alley length and decreased with structural complexity of the mazes. Locomotion became less stereotyped with increased experience, showing an increasing number of turns, less constant velocity, loss of the initial preference for outward leading alleys and weakening of the forward tendency at reentry from side alleys into hexagonal alleys. In contrast to these qualitative changes of locomotion, the amount of activity remained almost unchanged throughout the experiment. The results suggest that these increases in locomotion complexity depend upon complex interactions between experience and stimulus content of the mazes.     

Self‐awareness in Young Adults with Down Syndrome: I. Awareness of Down syndrome and disability

The limited literature on awareness of differences and stigma in people with intellectual disabilities is largely sociological, emphasises pathology, and has rarely used a developmental perspective with representative samples. Interviews, photographs and standardised tests were used to investigate such awareness with 77 young adults with Down syndrome and their parents. Awareness and social categorisation were significantly associated with verbal mental age, and closely approximated the typical social‐cognitive developmental sequence. No associations were found between awareness and chronological age, parent telling, gender, and mainstream experience. Only those with verbal mental ages from around 8 years were making relative social comparisons and beginning to form complex social categories of Down syndrome/disability. Around 13% were rated as showing a negative emotional reaction to Down syndrome/disability, and most of these were male. A similar percentage, mostly female and with higher verbal mental ages, discussed concerns and limitations. Even so, they all had high self‐esteem and awareness of Down syndrome and disability did not appear to be a major issue. A number of coping mechanisms to maintain a positive sense of self were suggested. It is argued that both sociological and developmental models are required to inform parent and professional attempts to facilitate self‐awareness.     

A study of auditory preferences in nonhandicapped infants and infants with Down's syndrome

11 infants with Down's syndrome (MA 9.2 months, CA 12.7 months) and 10 of 11 nonhandicapped infants (MA 9.6 months, CA 9.3 months) demonstrated that they could operate an automated device which enabled them to choose to listen to 1 of a pair of auditory signals. All subjects showed preferential responding. Both groups of infants showed a significant preference for nursery rhymes sung by a female voice rather than played on musical instruments. The infants with Down's syndrome had much longer response durations for the more complex auditory stimuli. The apparatus provides a useful technique for studying language development in both normal and abnormal populations.     

Adult support and the exploratory behavior of children with learning disabilities

Low- and moderate-exploratory children with learning disabilities engaged in exploratory behavior independently and with an adult who communicated support in one of two nonintrusive ways. Consistent with a developmental motivation perspective, low- and moderate-exploratory children showed higher levels of exploration under both kinds of supportive conditions.     

Children with Down syndrome use phonological knowledge in reading

Contrary to the findings of Cossu, Rossini &Marshall [(1993a), Cognition 46: 129–138], the present experiment showed a clear link between phonological awareness and reading performance in children with Down syndrome. Although metaphonologicalperformance was lower in children with Downsyndrome than in normal controls of the samereading level, phonological awareness andreading were significantly correlated in bothgroups. However, children with Down syndromeremained deficient in skills such as rhymingwhich are not practised as a result ofliteracy. These results are discussed withinthe framework of Gombert's metalinguisticdevelopment theory where, on the basis of aninitial phonological sensitivity, alphabeticreading is a pacemaker for the development ofexplicit phonological awareness.     

Training reading and phoneme awareness skills in children with Down syndrome

The authors report a short-term reading intervention study involving 15 children with Down syndrome (DS) who attended mainstream schools. The intervention programme taught children phoneme segmentation and blending skills in the context of learning letter-sounds and working with words in books. The children were taught by their learning support assistants, who received special training for this purpose. Compared to a waiting group, a group of eight children with DS improved significantly on measures of early literacy skills (letter-sound knowledge, Early Word Recognition) following eight weeks of intervention. The waiting group started to make progress once they received the intervention. Both groups maintained progress on the literacy measures five months after the intervention had finished. The results suggest that children with DS can benefit from structured, phonics-based reading intervention.     

Personal Reflections: quality of life research and Down syndrome

This paper attempts to illustrate some of the changes in research practice associated with and exemplified by quality of life studies. The critical relevance of personal perception is discussed. Finally some examples of research development in Down syndrome involving quality of life concepts are briefly described indicating the way quality of life studies can impact aims, direction, structure, and interpretation of research.