Visual Search Tasks - Essay Example

There are several types of research with various stimuli, while the most prevalent idea proposed for human visual search comes from A. Treisman (1980), who conducted research illustrating Feature integration theory. It asserts that a visual search is faster in presence of dissimilar background and the number of distracters involved in the background does not affect the time consumption in case of a feature search (a search that involves identification of a direct feature like color, shape, orientation or curvature). On the other hand, a conjunction search is affected widely by the number of distracters presented in the background. A conjunction search is defined as a search that does not involve a direct feature but a similarity of multiple features among the various objects. (For example, ‘blue square’ has similarities with ‘blue triangle’ and ‘red square’.)

            Consequent to the propositions, feature integration theory illustrates that those two searches consist of different methodologies for human visual search. Those methods are characterized as parallel searches and serial searches for a feature and conjunctive patterns.          As further illustrated in Feature Integration theory, feature search and conjunction search differ widely on time consumption patterns as conjunction search follows a twofold process which requires identifying the features and categorizing the conjunctions to create a pattern of search. The distracters found in the patterns are responsible for time consumption.

The feature-integration theory of attention suggests that attention must be directed serially to each stimulus in a display whenever conjunctions of more than one separable feature are needed to characterize or distinguish the possible objects (Treisman and Gelade, 1980)

There are several arguments and theoretical results that involve some serious diversions and modifications to this theory. However, most of the theories involve the base of feature integration which asserts that there are found clear differences in the types of searches when direct features are involved or eliminated.

Other theories and Guided search

            In contrast with feature integration theory, there is some proposition that offers different arguments and researches for visual search. A major theory is in the propositions of Wolfe (1989) who offers broad research for how visual search is not limited only to the factors if the searches are parallel or serial, but it also depends largely on the motivating factors for a visual search. Wolfe presents this theory as the guided search theory. In his propositions, several subjects were passed through the experiments with a varying number of stimuli, and the data outcome was measured over the graphs to provide a serious deflection from Feature integration patterns.

Subjects searched sets of items for targets defined by conjunctions of color and form, color and orientation, or color and size. Set size was varied and reaction times (RT) were measured. For many unpracticed subjects, the slopes of the resulting RT x Set Size functions are too shallow to be consistent with Treisman's feature integration model, which proposes a serial, self-terminating search for conjunctions (Jeremy M. Wolfe, 1989).

As those results offer a diversion in self-terminating serial search for conjunctions, Wolfe’s conclusion asserts that the assumption of feature integration is applicable only if the parallel processes guide attention.

Standard conjunction produces moderately efficient searches. In contrast, in a search for a T among Ls, there is no useful information in the parallel processes and the task reverts to a completely serial search. Our data can be accounted for within the feature integration model if and only if the parallel processes pass on useful information to guide the movements of the spotlight of attention (Jeremy M. Wolfe, 1989).

Resultantly Wolfe’s assertion put clear demarcations for how even feature search theory is applied in presence of a supportive model for visual guidance. (Yantis, 1993) Supports and explains the importance of guidance in a visual search task.  Similarly, there are several other offerings from various researches which provide objections and alternatives to feature integration theory. For example, experiments from (Duncan, 1989) considers human visual search to be more dependent on the rejection of distracters and thus based on attending the number of stimuli-similarities and inversely proportional to its measures.  Posner (1980) offers the visual search to be dependent on the area of single vision, quite wholly different proposition from Feature Integration.

Conclusions

            Thus, it comes out that feature integration theory has provided a base format for distinctions between the types of tasks that determine the time taken in a visual search. However, how much search type and set-size effects the time consumption is a matter of forwarding theories which proposes numerous important assumptions including the Guided search and other theories which try to assert that it is not only the search type and set size that determines the time consumption but there are other factors, such as the guiding environment in parallel searches, playing a major role in time determinations.

            How much effect the number of distracters makes on search type can be calculated straightly with the Feature integration propositions and its graphs, but there are some serious deflections in the graphs calculated on various patterns by other theorists. Resultantly, Feature integration provides a base format that is continuous on many patterns but shows diversions in certain cases that offer a wide range of assumptions and experimentations to be laid open for the theories of human visual search formats and effects of distracters and stimuli in different environments.