Patients With Left Spatial Neglect Also Neglect the “Left Side” of Time

Abstract

Previous research suggests that people construct mental time lines to represent and reason about time. However, is the ability to represent space truly necessary for representing events along a mental time line? Our results are the first to demonstrate that deficits in spatial representation (as a function of left hemispatial neglect) also result in deficits in representing events along the mental time line. Specifically, we show that patients with left hemispatial neglect have difficulty representing events that are associated with the past and, thus, fall to the left on the mental time line. These results demonstrate that representations of space and time share neural underpinnings and that representations of time have specific spatial properties (e.g., a left and a right side). Furthermore, it appears that intact spatial representations are necessary for at least some types of temporal representation.

Time in the eye of the beholder: Gaze position reveals spatial-temporal associations during encoding and memory retrieval of future and past

“…The procedure was adapted from Saj et al (2014). Participants were seated in front of the computer screen.…”

“…As in Saj et al (2014), participants were introduced to a fictional man named David. Since our participants (students) were younger compared to the participants in Saj et al's study (patients), we changed the age of the protagonist.…”

“…The items were objects or verbs that a fictive person liked to eat (egg, corn, hamburger, spaghetti, ice cream, apple, grapes, cake, sandwich, and pear), had in his apartment (clock, desk, kettle, vase, telephone, lamp, toaster, refrigerator, chair, and television), liked to wear (shoe, shirt, pants, watch, sock, tie, scarf, boot, belt, and coat), and liked to do (sailing, roller-skating, painting, playing football, playing the guitar, reading, flying a kite, playing tennis, skiing, and playing the trumpet) 10 years ago in the past, or that the same person will like to eat, will have in his apartment, will wear, and will like to do 10 years in the future. We used the same items as Saj et al (2014), with the difference that we did not use pictures of the items but audiofiles, presented via loudspeakers. We wanted to avoid that eye movement behavior was determined by specific properties of the visual images (e.g., mentally revisiting specific parts of the image during recall and recognition).…”

“…Thus it is possible that eye gaze position will reflect a past-left and future-right association already during encoding. In addition, the mental time line might be recruited to structure information in memory, and consequently influence information processing at a later stage, when the information is retrieved from memory (Saj et al, 2014). In a mental time travel task, we found that eye gaze shifted more rightward when participants thought about their personal future than when they thought about their past (Hartmann et al, 2014), thus we expect that eye gaze position will reflect a past-left and future-right association also during recall and recognition in this study.…”

“…In order to address this question, it is necessary to look at spatial-temporal associations during different stages of memory. A promising way to investigate spatialtemporal associations in different memory processes has recently been introduced by Saj, Fuhrman, Vuilleumier, and Boroditsky (2014). In their study, participants had to encode, recall, and recognize a list of images as belonging to the past or future.…”