Michael T. Carlin

Preschoolers' speed of locating a target symbol under different color conditions

A pressing decision in AAC concerns the organization of aided visual symbols. One recent proposal suggested that basic principles of visual processing may be important determinants of how easily a symbol is found in an array, and that this, in turn will influence more functional outcomes like symbol identification or use. This study examined the role of color on accuracy and speed of symbol location by 16 preschool children without disabilities. Participants searched for a target stimulus in an array of eight stimuli. In the same-color condition, the eight stimuli were all red; in the guided search condition, four of the stimuli were red and four were yellow; in the unique-color condition, all stimuli were unique colors. Accuracy was higher and reaction time was faster when stimuli were unique colors than when they were all one color. Reaction time and accuracy did not differ under the guided search and the color-unique conditions. The implications for AAC are discussed.

Incongruous item generation effects: a multiple-cue perspective.

In a series of studies, generation effects were obtained under encoding conditions designed to induce incongruous, unrelated item generation. Experiments 1 and 2, using free- and cued-recall measures, respectively, provided evidence that this unrelated generation effect was due to response-specific processing. Experiment 3 demonstrated a lack of relation between free recall and indices of clustering. A preliminary protocol study suggested that Ss generate multiple items in their search for appropriate unrelated responses. In Experiments 4 and 5, conditions designed to produce more extensive multiple generations demonstrated enhanced free recall. These results supported a multiple-cue account of facilitated recall for incongruous item generation. The multiple-cue perspective is consistent with traditional conceptualizations of memory, such as the principle of congruity, and contemporary distinctions between cue-target relational and item-specific processing.

Generative Processing and False Memories: When There Is No Cost

Encoding manipulations (e.g., levels of processing) that facilitate retention often result in greater numbers of false memories, a pattern referred to as the more is less effect (M. P. Toglia, J. S. Neuschatz, & K. A. Goodwin, 1999). The present experiments explored false memories under generative processing. In Experiments 1-3, using Deese-Roediger-McDermott (DRM) lists with items that were either read or generated, the authors found recognition and recall tests indicated generation effects for true memories but no increases in false memories (i.e., generation at no cost). In Experiment 4, in a departure from the DRM methodology, a cuing procedure resulted in a more is less pattern for congruous generation,and a no cost pattern for incongruous generation. This highlights the critical distinction between these encoding contexts.

Visual search in unidimensional arrays: A comparison between subjects with and without mental retardation

Abstract Through the utilization of unidimensional visual search tasks with homogeneous backgrounds, 16 individuals with mental retardation and 16 individuals without mental retardation were tested to determine whether the efficiency of search would vary as a function of dimension (color, form, size, and line orientation, ) and/or level of intelligence. Results indicated group by set size interactions for the dimensions of form and size, indicating intelligence-related differences in search efficiency for these dimensions. In addition, pronounced performance variability within the group of subjects with mental retardation was evident. Results demonstrated no difference in efficiency of search between groups for the dimensions of color and line orientation, thus indicating that the processes involved in speeded visual search were intact for these dimensions. These findings could lead to a greater understanding of the functional parameters of visual information processing within the population of individuals with mental retardation.

Guided Visual Search in Individuals With Mental Retardation

The ability of individuals with mental retardation to focus on task-relevant elements of complex visual arrays and increase visual-search efficiency was investigated. Initial assessments of visual-search efficiency were conducted to identify pairs of features for the form and size dimensions for which each participant demonstrated serial search. Subsequently, color was added as a defining feature that could guide search to a subset of the elements in the array. Results indicated that all of the individuals with mental retardation were able to limit attention to the task-relevant items on the guided search task, thus greatly reducing overall target identification times. Results show that individuals with mental retardation can demonstrate sophisticated visual selective attention skills when visual arrays are structured appropriately.

Enhancing Free-Recall Rates of Individuals With Mental Retardation

Generative encoding contexts promote activation of multiple retrieval routes and have been shown to enhance free-recall rates of individuals without mental retardation. The present extension to individuals with mental retardation involved a comparison of two encoding conditions: (a) fade-in, initially presenting pictures out of focus then slowly fading them into focus, and (b) fade-out, presenting pictures clearly then slowly blurring them. Results indicated that free-recall rates were greater for the fade-in items for the individuals with mental retardation and CA-matched comparisons, but not for the MA-matched group. These findings demonstrate the utility of a generative encoding context that does not involve verbal instruction for individuals with and without mental retardation.

Guiding visual attention during acquisition of matching-to-sample.

Matching-to-sample skills are involved in language acquisition and the development of basic reading and counting abilities. The rapid, even errorless, induction of matching performances in young children and individuals with mental retardation was demonstrated here through the structuring of a visual array so as to promote detection of the relevant stimulus. Implications for theory and application are discussed.

Veridical and false pictorial memory in individuals with and without mental retardation.

Veridical and false pictorial recognition were assessed in individuals with mental retardation; groups were matched for MA and CA. Pictures were viewed in either a generative or static format at acquisition. The individuals with mental retardation and those in the MA-matched group had higher rates of false memories for critical items and lower hit rates than did their CA-matched peers. The mental retardation group demonstrated an acquiescent response bias (i.e., high novel false-alarm rate). When data were corrected for this bias, those with mental retardation had significantly lower hit rates but equivalent false-alarm rates to the MA-matched participants. Results are discussed in terms of pictorial distinctiveness and within the frameworks of activation monitoring and fuzzy trace theory.

Detection of changes in naturalistic scenes: comparisons of individuals with and without mental retardation.

Abilities of individuals with and without mental retardation to search for and detect salient changes to naturalistic scenes were investigated using the flicker paradigm. Located in areas of central or marginal interest, changes involved an objects color, shape, or presence. Individuals with mental retardation required more time to detect changes of all types, and the magnitude of the group difference was more pronounced for marginal-interest changes. Supplemental eye-tracking data from 6 participants suggested that the basis of this effect was that individuals with mental retardation tended to maintain gaze in the region of central interest for longer periods of time prior to sampling the other areas of the scene. Implications for intelligence-related differences in visual attention are discussed.

Detection of Motion-defined Forms by Individuals with Mental Retardation and Autism: Evidence of Modifiability

Abstract Eight individuals with mental retardation and autism and 16 individuals without mental retardation or autism were studied with regard to their ability to detect the presence or absence of a form in a random-dot kinematogram (RDK). Those individuals that failed to demonstrate criterion performance (i.e., 85% correct) with the initial assessment (i.e., 50% density, 100% temporal correlation of target elements) were provided with a novel binary training procedure. The procedure involved response-based training in conjunction with a procedure in which the density of the surround in the visual array was incrementally increased. Subsequent to training, all subjects with mental retardation and autism successfully met criterion with the initial stimulus and proceeded to demonstrate performance comparable to individuals without mental retardation. The presence and generalization of training effects suggests that initial failures on such “preattentional” detection tasks may be due, at least in part, to post-perceptual factors.