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Jonathan J Marotta

Publications and source records attributed to Jonathan J Marotta.

3 recordsLinked to original sources

A new window into the interactions between perception and action.

Traditionally, viewing window paradigms have been used to evaluate perceptual features useful in object identification. Participants are presented with a degraded picture of an object on a computer monitor and are asked to identify the object as quickly as possible. A small, user controlled area (the "window") displays the underlying image with normal clarity. Despite their traditional role, viewing window tasks require visuomotor processing, which can be manipulated to illuminate the interactions between the "perception" and "action" based cortical visual streams. As participants performed the present experiment, response times and movement of the window were recorded. The participant's movement of the window was analyzed (the visuomotor scanning pattern), separating the image into four equal sized quadrants and then examining the percentage of time spent in each. A main-effect of quadrant was found, demonstrating the ability of this procedure to identify vertical and horizontal asymmetries in visuomotor scan patterns elicited by the presented objects. This research demonstrates the feasibility of the viewing window as a method of examining the interactions between perceptual and motor information. Importantly, results indicate that the viewing window procedure has the ability discriminate any gross asymmetries in a participant's visuomotor scanpath used to identify these common objects.

Adolescent↗

Detailed exploration of face-related processing in congenital prosopagnosia: 1. Behavioral findings.

We show that five individuals with congenital prosopagnosia (CP) are impaired at face recognition and discrimination and do not exhibit the normal superiority for upright over inverted faces despite intact visual acuity, low-level vision and intelligence, and in the absence of any obvious neural concomitant. Interestingly, the deficit is not limited to faces: The CP individuals were also impaired at discriminating common objects and novel objects although to a lesser extent than discriminating faces. The perceptual deficit may be attributable to a more fundamental visual processing disorder; the CP individuals exhibited difficulty in deriving global configurations from simple visual stimuli, even with extended exposure duration and considerable perceptual support in the image. Deriving a global configuration from local components is more critical for faces than for other objects, perhaps accounting for the exaggerated deficit in face processing. These findings elucidate the psychological mechanisms underlying CP and support the link between configural and face processing.

Adult↗

Task-specific sensorimotor adaptation to reversing prisms.

We tested between three levels of visuospatial adaptation (global map, parallel feature modules, and parallel sensorimotor transformations) by training subjects to reach and grasp virtual objects viewed through a left-right reversing prism, with either visual location or orientation feedback. Even though spatial information about the global left-right reversal was present in every training session, subjects trained with location feedback reached to the correct location but with the wrong (reversed) grasp orientation. Subjects trained with orientation feedback showed the opposite pattern. These errors were task-specific and not feature-specific; subjects trained to correctly grasp visually reversed-oriented bars failed to show knowledge of the reversal when asked to point to the end locations of these bars. These results show that adaptation to visuospatial distortion--even global reversals--is implemented through learning rules that operate on parallel sensorimotor transformations (e.g., reach vs. grasp).

Adaptation, Physiological↗