Representation Of Target Object Research Articles

Activation of new attentional templates for real-world objects in visual search.

Visual search is controlled by representations of target objects (attentional templates). Such templates are often activated in response to verbal descriptions of search targets, but it is unclear whether search can be guided effectively by such verbal cues. We measured ERPs to track the activation of attentional templates for new target objects defined by word cues. On each trial run, a word cue was followed by three search displays that contained the cued target object among three distractors. Targets were detected more slowly in the first display of each trial run, and the N2pc component (an ERP marker of attentional target selection) was attenuated and delayed for the first relative to the two successive presentations of a particular target object, demonstrating limitations in the ability of word cues to activate effective attentional templates. N2pc components to target objects in the first display were strongly affected by differences in object imageability (i.e., the ability of word cues to activate a target-matching visual representation). These differences were no longer present for the second presentation of the same target objects, indicating that a single perceptual encounter is sufficient to activate a precise attentional template. Our results demonstrate the superiority of visual over verbal target specifications in the control of visual search, highlight the fact that verbal descriptions are more effective for some objects than others, and suggest that the attentional templates that guide search for particular real-world target objects are analog visual representations.

Is the representation of target objects independent of their surrounding

Is the representation of target objects independent of their surrounding

Masked targets trigger event-related potentials indexing shifts of attention but not error detection

To carry out tasks with the highest possible efficiency we have developed executive mechanisms that monitor task performance and optimize cognitive processing. It has been hypothesized that these executive mechanisms operate even without conscious awareness to maximize their sensitivity to task-relevant outcomes. To test this hypothesis the present study examined the error-related negativity (ERN), an electrophysiological index of the performance-monitoring neural circuitry, during masked visual search. The findings show that representations of target objects that are processed perceptually, but not to the level of awareness, fail to elicit an ERN despite the ability of these targets to elicit a shift of attention. These findings indicate that the performance-monitoring mechanism indexed by the ERN requires target information to be processed to the level of awareness for a mismatch between stimulus and response to be detected.

Change trajectories and key biotopes—Assessing landscape dynamics and sustainability

This paper presents a methodological synthesis of two congruent approaches into a common landscape change trajectory analysis and the assessment of landscape dynamics and sustainability. The emphasis of the analysis is on the retrospective relationship between the past and the present-day landscape patterns and associated key biotopes. The example key biotopes, oak woodlands and grasslands, represent valuable habitats in the hemiboreal landscapes of Finland and Sweden. The paper presents a conceptual stepwise approach for change trajectory analysis utilising multiple spatio-temporal data and techniques available in image processing and geographical information systems (GIS) including the following steps: (I) specification of spatio-temporal data and their representation of target objects, (II) the choice of direct or indirect change trajectory analysis, (III) hierarchical structuring of landscape information, (IV) compilation of landscape information into a GIS database, and (V) identification of paths for landscape change trajectory analysis. In this case study, we have focused on three interlinked trajectory analysis approaches, and their role in the assessment of landscape sustainability from a potential biodiversity perspective. We conclude that proposed landscape change trajectory analysis can improve the assessment of the key biotopes as well as present-day landscape characteristics, in maintaining biodiversity and related ecological values by providing information on landscape stability, continuity, change processes and boundary dynamics. This approach can be useful in the assessment of natural capital, but requires data-specific and context sensitive data processing and analysis solutions. The results should be interpreted as an approximation and generalisation of the spatio-temporal complexity of landscape reality and therefore be used in conjunction with additional habitat function measures.