Ian P. Rasmussen

Binding Objects to Locations: The Relationship Between Object Files and Visual Working Memory

The relationship between object files and visual working memory (VWM) was investigated in a new paradigm combining features of traditional VWM experiments (color change detection) and object-file experiments (memory for the properties of moving objects). Object-file theory was found to account for a key component of object-position binding in VWM: With motion, color memory came to be associated with the new locations of objects. However, robust binding to the original locations was found despite clear evidence that the objects had moved. This latter binding appears to constitute a scene-based component in VWM, which codes object location relative to the abstract spatial configuration of the display and is largely insensitive to the dynamic properties of objects.

The Nesting of Search Contexts Within Natural Scenes: Evidence From Contextual Cuing

In a contextual cuing paradigm, we examined how memory for the spatial structure of a natural scene guides visual search. Participants searched through arrays of objects that were embedded within depictions of real-world scenes. If a repeated search array was associated with a single scene during study, then array repetition produced significant contextual cuing. However, expression of that learning was dependent on instantiating the original scene in which the learning occurred: Contextual cuing was disrupted when the repeated array was transferred to a different scene. Such scene-specific learning was not absolute, however. Under conditions of high scene variability, repeated search array were learned independently of the scene background. These data suggest that when a consistent environmental structure is available, spatial representations supporting visual search are organized hierarchically, with memory for functional subregions of an environment nested within a representation of the larger scene.

Guidance of Attention to Objects and Locations by Long-Term Memory of Natural Scenes

Four flicker change-detection experiments demonstrate that scene-specific long-term memory guides attention to both behaviorally relevant locations and objects within a familiar scene. Participants performed an initial block of change-detection trials, detecting the addition of an object to a natural scene. After a 30-min delay, participants performed an unanticipated 2nd block of trials. When the same scene occurred in the 2nd block, the change within the scene was (a) identical to the original change, (b) a new object appearing in the original change location, (c) the same object appearing in a new location, or (d) a new object appearing in a new location. Results suggest that attention is rapidly allocated to previously relevant locations and then to previously relevant objects. This pattern of locations dominating objects remained when object identity information was made more salient. Eye tracking verified that scene memory results in more direct scan paths to previously relevant locations and objects. This contextual guidance suggests that a high-capacity long-term memory for scenes is used to insure that limited attentional capacity is allocated efficiently rather than being squandered.

The rhythm aftereffect: Support for time sensitive neurons with broad overlapping tuning curves

Ivry [Ivry, R. B. (1996). The representation of temporal information in perception and motor control. Current Opinion in Neurobiology, 6, 851-857.] proposed that explicit coding of brief time intervals is accomplished by neurons that are tuned to a preferred temporal interval and have broad overlapping tuning curves. This proposal is analogous to the orientation selective cells in visual area V1. To test this proposal, we used a temporal analog to the visual tilt aftereffect. After adapting to a fast auditory rhythm, a moderately fast test rhythm (400 ms between beats) seemed slow and vice versa. If the speed of the adapting rhythm was made too disparate from speed of the test rhythm the effect was diminished. The effect occurred whether the adapting and test stimuli were presented to the same or different ears, but did not occur when an auditory adapting rhythm was followed by a visual test rhythm. Results support the proposition that explicit time information is coded by neural units tuned to specific temporal intervals with broad overlapping tuning curves. In addition, it appears that there is a single timing mechanism for each incoming sensory mode, but distinct timers for different modes.

“A Fire in the Blood”: Metaphors of Bipolar Disorder in Jamison’s An Unquiet Mind

Content analysis of three chapters of Jamison’s memoir, An Unquiet Mind, shows that depression, mania, and Bipolar Disorder have a common metaphoric core as a sequential process of suffering and adversity that is a form of malevolence and destruction. Depression was down and in, while mania was up, in and distant, circular and zigzag, a powerful force of quickness and motion, fieriness,strangeness, seduction, expansive extravagance, and acuity. Bipolar Disorder is down and away and a sequential and cyclical process that partakes of the metaphors of its component moods. We conclude that metaphors of mood disorders share a number of structural features and are consistent across different authors.

The capacity for spatial updating in visual short-term memory

Participants can update memory for the binding of perceptual features to object locations, but only for approximately two objects, which is significantly smaller than VSTM capacity and significantly smaller than Cowan, N., Elliott, E. M., Saults, J. S., Morey, C. C., Mattox, S., Ismajatulina, A., et al. (2005). On the capacity of attention: Its estimation and its role in working memory and cognitive aptitudes. Cognitive Psychology, 51, 42-100. , 1997).

The interaction between global and local scene features in contextual cueing

With local and global contexts clearly segregated, and with the target appearing only in the local array, the present method provided a strong test of our hypothesis that the two sources of information are integrated. During the training block, we found contextual cueing when subjects searched in repeated arrays (global and local predictive), suggesting that participants were sensitive to the spatial regularity in either global scene, th l l b th driven primarily by memory for local elements near the target location (Olson & Chun, 2002). In contrast, studies using real-world scene stimuli have found that contextual cueing is driven primarily by memory for global scene features (Brockmole et al., 2006). Participants completed a training session of 24 blocks of 16 trials. Within a block, each of the 16 global scene items appeared once. Training e oca array or o .