Mark S. Strauss

Infant perception of numerosity.

A multiple habituation paradigm was used to determine whether 10--12-month-old infants were able to discriminate between visual arrays which differed only in their numerosity (2 vs. 3, 3, vs. 4, or 4 vs. 5 items). 96 infants were tested in one of two conditions. In the heterogeneous condition, infants were habituated to a series of slides in which only the number of items remained invariant, while the item type (e.g., dogs, houses, etc.), size, and position varied on each slide. In the homogeneous condition, both the item type (chicks) and number remained invariant, while the size and position of the stimuli varied. Infants in both conditions were then tested with slides which contained either N + 1 or N - 1 items. The results demonstrated that, regardless of condition (homogeneous/heterogeneous), infants were able to discriminate between 2 and 3 items and unable to discriminate between 4 and 5 items. For the 3 versus 4 discrimination, a condition x sex interaction indicated that females discriminated between the items in the homogeneous condition while males were able to make the discrimination in the heterogeneous condition. Since the subjects in this study were preverbal infants, the results suggest that early counting skills are preceded by a more perceptual awareness of numerosity.

The Development of Emotion Recognition in Individuals With Autism

Emotion recognition was investigated in typically developing individuals and individuals with autism. Experiment 1 tested children (5-7 years, n = 37) with brief video displays of facial expressions that varied in subtlety. Children with autism performed worse than the control children. In Experiment 2, 3 age groups (8-12 years, n = 49; 13-17 years, n = 49; and adults n = 45) were tested on the same stimuli. Whereas the performance of control individuals was best in the adult group, the performance of individuals with autism was similar in all age groups. Results are discussed with respect to underlying cognitive processes that may be affecting the development of emotion recognition in individuals with autism.

Comparison of Eye Movements over Faces in Photographic Positives and Negatives

Eye movements were recorded while subjects viewed ordinary portraits and photographic negatives of those portraits. Under both conditions they first studied sixteen portraits and then tried to decide which of forty-eight portraits they had just seen. They made more errors of recognition while viewing negatives, and their fixation patterns were significantly altered: there was a decrease in the percentage of fixations directed to the eyes, nose, and mouth, and an increase for such details as the ears, cheeks, chin, cap, and necktie. There was also a decrease in the ratio of fixations to the most fixated detail compared to the least fixated detail.

Eye movements during search for coded and uncoded targets

Eye movements and search time of four subjects were studied as they searched for a target dial in a 4 х 4 array of dials which were differentiated by (1) color, (2) shape, (3) a combination of color and shape, or (4) were uncoded. Subjects did not exhibit a characteristic scanpath, and method of scanning did not relate to search time. Search time varied reliably among conditions; it was generally shortest in the color condition, followed by color shape, shape, and the uncoded condition. Subjects were capable of using both shape and color simultaneously. Search time was strongly associated with the average number of fixations required for target detection but not with other measures of eye movements. Fixation duration was a particularly inconsistent measure.

Category Formation in Autism: Can Individuals with Autism Form Categories and Prototypes of Dot Patterns?

There is a growing amount of evidence suggesting that individuals with autism have difficulty with categorization. One basic cognitive ability that may underlie this difficulty is the ability to abstract a prototype. The current study examined prototype and category formation with dot patterns in high-functioning adults with autism and matched controls. Individuals with autism were found to have difficulty forming prototypes and categories of dot patterns. The eye-tracking data did not reveal any between group differences in attention to the dot patterns. However, relationships between performance and intelligence in the autism group suggest possible processing differences between the groups. Results are consistent with previous studies that have found deficits in prototype formation and extend these deficits to dot patterns.

Prototype Formation in Autism: Can Individuals with Autism Abstract Facial Prototypes?

Prototype formation is a critical skill for category learning. Research suggests that individuals with autism may have a deficit in prototype formation of some objects; however, results are mixed. This study used a natural category, faces, to further examine prototype formation in high‐functioning individuals with autism. High‐functioning children (age 8–13 years) and adults with autism (age 17–53 years) and matched controls were tested in a facial prototype formation task that has been used to test prototype formation abilities in typically developing infants and adults [Strauss, 1979 ]. Participants were familiarized to a series of faces depicting subtle variations in the spatial distance of facial features, and were then given a forced choice familiarity test between the mean prototype and the mode prototype. Overall, individuals in the autism group were significantly less likely to select the mean prototype face. Even though the children with autism showed this difference in prototype formation, this pattern was driven primarily by the adults, because the adults with autism were approximately four times less likely to select the mean prototype than were the control adults. These results provide further evidence that individuals with autism have difficulty abstracting subtle spatial information that is necessary not only for the formation of a mean prototype, but also for categorizing faces and objects.

Can Individuals with Autism Abstract Prototypes of Natural Faces

There is a growing amount of evidence suggesting that individuals with autism have difficulty with face processing. One basic cognitive ability that may underlie face processing difficulties is the ability to abstract a prototype. The current study examined prototype formation with natural faces using eye-tracking in high-functioning adults with autism and matched controls. Individuals with autism were found to have significant difficulty forming prototypes of natural faces. The eye-tracking data did not reveal any between group differences in the general pattern of attention to the faces, indicating that these difficulties were not due to attentional factors. Results are consistent with previous studies that have found a deficit in prototype formation and extend these deficits to natural faces.

Gender Discrimination of Eyes and Mouths by Individuals with Autism

Evidence remains mixed about whether individuals with autism look less to eyes and whether they look more at mouths. Few studies have examined how spontaneous attention to facial features relates to face processing abilities. This study tested the ability to discriminate gender from facial features, namely eyes and mouths, by comparing accuracy scores of 17 children with autism and 15 adults with autism to 17 typically developing children and 15 typically developing adults. Results indicated that all participants regardless of diagnosis discriminated gender more accurately from eyes than from mouths. However, results indicated that compared to adults without autism, adults with autism were significantly worse at discriminating gender from eyes.

The Development of Infant Memory

The concept of memory has undergone a profound change in this century. In the late nineteenth century Ebbinghaus (1885/1964), the first experimentalist to study memory systematically, offered a view of memory that dominated research and theory until recently. His view had several components. First, he thought of memory as an isolable system, capable of being understood independent of other aspects of mind, such as perception, thought, and knowledge. This in part motivated his use of the nonsense syllable. He wanted an experimental unit that was devoid of meaning, which he clearly viewed as a complication for the study of memory. Second, he believed that memory could be understood in mechanistic terms. The formation of associations in memory resulted primarily from repeated experience of items in contiguity. This view reflected the atomistic view of mind that characterized the philosophical and physiological roots from which modern experimental psychology originated (see Boring, 1950, for details). Third, his goal was to establish quantitative laws that described the regularities by which associations were acquired and forgotten. His pioneering research provided the first reports of such quantitative relationships, establishing a model for research on memory for much of the following century.

A Lack of Left Visual Field Bias when Individuals with Autism Process Faces

It has been established that typically developing individuals have a bias to attend to facial information in the left visual field (LVF) more than in the right visual field. This bias is thought to arise from the right hemisphere’s advantage for processing facial information, with evidence suggesting it to be driven by the configural demands of face processing. Considering research showing that individuals with autism have impaired face processing abilities, with marked deficits in configural processing, it was hypothesized that they would not demonstrate a LVF bias for faces. Eye-tracking technology was used to show that individuals with autism were not spontaneously biased to facial information in the LVF, in contrast to a control group, while discriminating facial gender.