Olivia C. Adkins

The visual perception of distance ratios in physical space

Past studies have consistently demonstrated that human observers cannot accurately perceive environmental distances. Even so, we obviously detect sufficient spatial information to meet the demands of everyday life. In the current experiment, ten younger adults (mean age was 21.8years) and ten older adults (mean age was 72.3years) estimated distance ratios in physical space. On any given trial, observers judged how long one distance interval was relative to another. The 18 stimulus ratios ranged from 1.0 to 9.5; the observers judged each stimulus ratio three times. The average correlation coefficient relating actual distance ratios to perceived ratios was identical (r=0.87) for both younger and older age groups. Despite this strong relationship between perception and reality, the judgments of many individual observers were inaccurate. For example, ten percent of the observers overestimated the stimulus ratios, while fifty percent underestimated the stimulus ratios. Although both under- and overestimation occurred in the current experiment, the results nevertheless demonstrate that human adults can reliably compare environmental distances in different directions.

The visual perception of distance ratios outdoors

We conducted an experiment to evaluate the ability of 32 younger and older adults to visually perceive distances in an outdoor setting. On any given trial, the observers viewed 2 environmental distances and were required to estimate the distance ratio—the length of the (usually) larger distance relative to that of the shorter. The stimulus distance ratios ranged from 1.0 (the stimulus distances were identical) to 8.0 (1 distance interval was 8.0 times longer than the other). The stimulus distances were presented within a 26 m × 60 m portion of a grassy field. The observers were able to reliably estimate the stimulus distance ratios: The overall Pearson r correlation coefficient relating the judged and actual distance ratios was 0.762. Fifty-eight percent of the variance in the observers’ perceived distance ratios could thus be accounted for by variations in the actual stimulus ratios. About half of the observers significantly underestimated the distance ratios, while the judgments of the remainder were essentially accurate. Significant modulatory effects of sex and age occurred, such that the male observers’ judgments were the most precise, while those of the older males were the most accurate.

Aging and Haptic-Visual Solid Shape Matching

A total of 36 younger (mean age = 21.3 years) and older adults (mean age = 73.8 years) haptically explored plastic copies of naturally shaped objects (bell peppers, Capsicum annuum) one at a time for 7 s each. The participants’ task was to then choose which of 12 concurrently visible objects had the same solid shape as the one they felt. The younger and older participants explored the object shapes using either one, three, or five fingers (there were six participants for each combination of number of fingers and age group). The outcome was different from that of previous research conducted with manmade objects. Unlike Jansson and Monaci (2006), we found that for most objects, our participants’ performance was unaffected by variations in the number of fingers used for haptic exploration. While there was no significant overall effect of the number of fingers, there was a significant main effect of age. The younger adults’ shape matching performance was 48.6% higher than that of the older adults. When perceiving naturally shaped objects such as bell peppers, it appears that the usage of a single finger can be as effective as haptic exploration with a whole complement of five fingers.

Aging and the Haptic Perception of Material Properties.

The ability of 26 younger (mean age was 22.5 years) and older adults (mean age was 72.6 years) to haptically perceive material properties was evaluated. The participants manually explored (for 5 seconds) 42 surfaces twice and placed each of these 84 experimental stimuli into one of seven categories: paper, plastic, metal, wood, stone, fabric, and fur/leather. In general, the participants were best able to identify fur/leather and wood materials; in contrast, recognition performance was worst for stone and paper. Despite similar overall patterns of performance for younger and older participants, the younger adults’ recognition accuracies were 26.5% higher. The participants’ tactile acuities (assessed by tactile grating orientation discrimination) affected their ability to identify surface material. In particular, the Pearson r correlation coefficient relating the participants’ grating orientation thresholds and their material identification performance was −0.8: The higher the participants’ thresholds, the lower the material recognition ability. While older adults are able to effectively perceive the solid shape of environmental objects using the sense of touch, their ability to perceive surface materials is significantly compromised.

Development of a Student Interest in Mathematics Scale for Gifted and Talented Programming Identification

The study’s purpose was to develop and validate a scale for assessing interest in mathematics among elementary students as part of an identification protocol for gifted and talented programming. Lohman recommends assessment of interest as a critical element within the ideal approach to identification. Hidi and Renninger’s Four-Phase Interest Development Model was identified as the theoretical model most closely aligned to identified interest factors. Their model along with current research literature informed and guided the creation of the measure. Items were created to assess emotion, value, perceived knowledge, and behavioral engagement in and outside of school. Three waves of data were collected utilizing second through sixth graders. The first exploratory factor analysis (EFA) resulted in the deletion of one factor. The second EFA reaffirmed the four-factor structure; in addition, the number of items was reduced. The confirmatory factor analysis resulted in a good model fit, supporting factor validity.

Aging and visual 3-D shape recognition from motion

Two experiments were conducted to evaluate the ability of younger and older adults to recognize 3-D object shape from patterns of optical motion. In Experiment 1, participants were required to identify dotted surfaces that rotated in depth (i.e., surface structure portrayed using the kinetic depth effect). The task difficulty was manipulated by limiting the surface point lifetimes within the stimulus apparent motion sequences. In Experiment 2, the participants identified solid, naturally shaped objects (replicas of bell peppers, Capsicum annuum) that were defined by occlusion boundary contours, patterns of specular highlights, or combined optical patterns containing both boundary contours and specular highlights. Significant and adverse effects of increased age were found in both experiments. Despite the fact that previous research has found that increases in age do not reduce solid shape discrimination, our current results indicated that the same conclusion does not hold for shape identification. We demonstrated that aging results in a reduction in the ability to visually recognize 3-D shape independent of how the 3-D structure is defined (motions of isolated points, deformations of smooth optical fields containing specular highlights, etc.).

The Visual Aesthetics of Snowflakes

In two experiments, participants evaluated the perceived beauty of snowflakes and solid objects. The snowflake silhouettes used as experimental stimuli were created from photographs of natural snowflakes. Both the snowflake silhouettes and computer-generated solid objects varied in complexity. In Experiment 1, 204 participants selected the single snowflake and single solid object that was the most beautiful. In Experiment 2, 33 participants rated the perceived complexity and beauty of the entire set of 100 snowflakes and solid objects. When considered as a group, the participants’ results for the solid objects replicated previous findings: The most and least complex objects were perceived as being the most beautiful. This pattern did not necessarily occur, however, for individual participants. Some participants in Experiment 2, for example, found only complex solid objects to be most beautiful (N = 10); other participants found only the simple solid objects to be most beautiful (N = 11). Additional participants perceived both the most and least complex solid objects to be beautiful (N = 10), while one participant only found moderately complex solid objects to be most beautiful. The results for the snowflakes were more uniform: 91% of participants perceived only the complex snowflakes as being most beautiful.