Biomedical subjects

Tamara L Watson

Publications and source records attributed to Tamara L Watson.

6 recordsLinked to original sources

PubMed2006

Orientation dependence of the orientation-contingent face aftereffect.

Prolonged exposure to upright and inverted female and male faces produces opposite effects on subsequent judgments of the sex of faces depending on their orientation. We show that the magnitude of this orientation-contingent gender aftereffect can be predicted from simple aftereffects induced separately at the same orientations. The contingent aftereffect can also be induced in faces tilted 90 degrees to the right and left, eliminating any difference in face-processing strategy that may be in operation with upright and inverted faces. This suggests that neurons employing a single face encoding strategy can be activated in an orientation-specific manner.

Face↗

PubMed2004

Orientation-contingent face aftereffects and implications for face-coding mechanisms.

Humans have an impressive ability to discriminate between faces despite their similarity as visual patterns. This expertise relies on configural coding of spatial relations between face features and/or holistic coding of overall facial structure. These expert face-coding mechanisms appear to be engaged most effectively by upright faces, with inverted faces engaging primarily feature-coding mechanisms. We show that opposite figural aftereffects can be induced simultaneously for upright and inverted faces, demonstrating that distinct neural populations code upright and inverted faces. This result also suggests that expert (upright) face-coding mechanisms can be selectively adapted. These aftereffects occur for judgments of face normality and face gender and are robust to changes in face size, ruling out adaptation of low-level, retinotopically organized coding mechanisms. Our results suggest a resolution of a paradox in the face recognition literature. Neuroimaging studies have found surprisingly little orientation selectivity in the fusiform face area (FFA) despite evidence that this region plays a role in expert face coding and that expert face-coding mechanisms are selectively engaged by upright faces. Our results, demonstrating orientation-contingent adaptation of face-coding mechanisms, suggest that the FFA's apparent lack of orientation selectivity may be an artifact of averaging across distinct populations within the FFA that respond to upright and inverted faces.

Adult↗

PubMed2004

Perceptual grouping of biological motion promotes binocular rivalry.

Investigation of perceptual rivalry between conflicting stimuli presented one to each eye can further understanding of the neural underpinnings of conscious visual perception. During rivalry, visual awareness fluctuates between perceptions of the two stimuli. Here, we demonstrate that high-level perceptual grouping can promote rivalry between stimulus pairs that would otherwise be perceived as nonrivalrous. Perceptual grouping was generated with point-light walker stimuli that simulate human motion, visible only as lights placed on the joints. Although such walking figures are unrecognizable when stationary, recognition judgments as complex as gender and identity can accurately be made from animated displays, demonstrating the efficiency with which our visual system can group dynamic local signals into a globally coherent walking figure. We find that point-light walker stimuli presented one to each eye and in different colors and configurations results in strong rivalry. However, rivalry is minimal when the two walkers are split between the eyes or both presented to one eye. This pattern of results suggests that processing animated walker figures promotes rivalry between signals from the two eyes rather than between higher-level representations of the walkers. This leads us to hypothesize that awareness during binocular rivalry involves the integrated activity of high-level perceptual mechanisms in conjunction with lower-level ocular suppression modulated via cortical feedback.

Dominance, Ocular↗

PubMed2003

Fitting the mind to the world: face adaptation and attractiveness aftereffects.

Average faces are attractive, but what is average depends on experience. We examined the effect of brief exposure to consistent facial distortions on what looks normal (average) and what looks attractive. Adaptation to a consistent distortion shifted what looked most normal, and what looked most attractive, toward that distortion. These normality and attractiveness aftereffects occurred when the adapting and test faces differed in orientation by 90 degrees (+45 degrees vs. -45 degrees ), suggesting adaptation of high-level neurons whose coding is not strictly retino- topic. Our results suggest that perceptual adaptation can rapidly recalibrate people's preferences to fit the faces they see. The results also suggest that average faces are attractive because of their central location in a distribution of faces (i.e., prototypicality), rather than because of any intrinsic appeal of particular physical characteristics. Recalibration of preferences may have important consequences, given the powerful effects of perceived attractiveness on person perception, mate choice, social interactions, and social outcomes for individuals.

Choice Behavior↗

PubMed2003

Pulling faces: an investigation of the face-distortion aftereffect.

After adaptation to a face distorted to look unnaturally thin or fat, a normal face appears distorted in the opposite direction (Webster and MacLin 1999 Psychonomic Bulletin & Review 6 647-653). When the adapting face is oriented 45 degrees from vertically upright and the test face 45 degrees in the opposite direction, the axis of perceived distortion changes with the orientation of the face. The magnitude of this aftereffect shows a reduction of approximately 40% from that found when both adapting and test faces are tilted identically. This finding suggests that to a large degree the aftereffect is mediated not by low-level retinotopic (image-based) visual mechanisms but at a higher level of object-based processing. Aftereffects of a similar magnitude are obtained when adapting and test images are both either upright or inverted, or for an upright adapter and an inverted test; but aftereffects are smaller when the adapter is inverted and the test upright. This pattern of results suggests that the face-distortion aftereffect is mediated by object-processing mechanisms including, but not restricted to, configurational face-processing mechanisms.

Adaptation, Psychological↗

PubMed2002

Formulary management of colony-stimulating factors.

The outcome of a formulary interchange from filgrastim to sargramostim for the amelioration of neutropenia for outpatients receiving myelosuppressive chemotherapy was evaluated. The pharmacy department at the James Graham Brown Cancer Center of the University of Louisville Hospital implemented a therapeutic interchange program by following the Joint Commission on Accreditation of Healthcare Organizations performance methodology, incorporating four key elements: plan, do, check, and act. After the pharmacy and therapeutics committee agreed that filgrastim and sargramostim are therapeutically equivalent, the pharmacy initiated the interchange, with a commitment to collect outcomes data to analyze the impact of the program on patient outcomes. Inclusion criteria included patient age of > or = 18 years, the presence of solid tumors or lymphoma, and current treatment with traditional chemotherapy. Patient demographics and cycle-specific data were collected for 31 patients receiving sargramostim and 20 patients receiving filgrastim from August 2000 to July 2001. Absolute neutrophil counts (ANCs) were measured before initiating and after discontinuing colony-stimulating factors. The majority (70%) of all growth factor use was initiated within one to four days of the last chemotherapy dose. No appreciable difference was found between agents for median ANC at any measured time point. The majority of patients exceeded the target ANC of 1500 cells/mm3 at the time of growth factor discontinuation. There were no significant differences in the number of patients that had adverse effects or in the number of cycles resulting in an adverse event between groups. Sargramostim demonstrated a 21% cost savings over filgrastim ($1036 versus $1318, respectively). The formulary switch from filgrastim to sargramostim resulted in a significant cost savings for the institution without increasing incidence of adverse effects and negative outcomes associated with growth factor use.

Chemistry, Pharmaceutical↗