Biomedical subjects

Jay Friedenberg

Publications and source records attributed to Jay Friedenberg.

3 recordsLinked to original sources

PubMed2004

Hierarchical number estimation.

We investigated number estimation using dot patterns grouped by proximity into larger clusters. Participants estimated the number of dots and clusters in separate trials. Estimation was most accurate when the numbers of elements on both scales were the same. When the number of elements on the unattended scale was higher, overestimation occurred. Conversely, when the number of elements on the unattended scale was lower, underestimation occurred. In Experiment 2, response cues were blocked to reduce any tendency toward attending the irrelevant level. The results were essentially unchanged, indicating response confusion alone cannot account for the effect. The data support the existence of an opposite scale effect in which the number of elements at the unattended level influence the processing of number.

Adult↗

PubMed2002

No within-object advantage for detection of rotation.

It is known that in a detection task the type of rigid transformation to be detected (reflection vs. translation) interacts with the type of display (closed vs. open contours). The advantage for closed contours found with reflection is believed to be a general within-object advantage, whilst the advantage for open contours found with translation is an exception, described as a lock-and-key process (Acta Psychol. 95 (1997) 119). We tested rotation, using a reaction time paradigm, and found the same result as for translation. Moreover, we found that the critical factor is not the number of objects present, rather it is whether the comparison is made across a surface or across an aperture between surfaces. Post-experiment interviews did not confirm any difference for observers who reported using a conscious lock-and-key mental transformation. We speculate that seeing a translation or a rotation across a closed figure is difficult because the closure of the figure emphasises the mismatch of the contour polarities on the two sides of the figure. That is, there may be a closed object advantage for detecting a difference in polarity which interferes with the task of detecting a regularity in shape. Evidence from the analysis of foil rejection trials supports such a speculation.

Adult↗

PubMed2002

Perception of two-body center of mass.

Participants estimated the perceptual center of mass between two horizontally oriented black dots varying in size and distance. Experiment 1 showed that estimates, measured as distance from the larger dot's center, decreased with an increase in size ratio between the dots and a decrease in the distance between them, as predicted by the physical center-of-mass equation. The results were replicated and extended in further experiments with different ratios and distances. In all experiments, the true center was consistently overestimated, either because the stimuli were perceived in a low dimensionality or because of a hesitancy to place estimates near the larger dot's edge. In Experiment 4, the center was deliberately placed near this edge for one- and two-dimensional solutions. Participants still overestimated, indicating an "edge effect" as responsible.

Adolescent↗