Читать книгу Cognitive Flexibility - Evelyne Clement - Страница 13

One of the best known measurements of flexibility, or at least the most widely used and cited in this field, is the Wisconsin Card Sorting Test (WCST; Grant and Berg (1948)). This task consists of sorting cards, in which no explicit instructions are given and the sorting rule must be inferred on the basis of feedback (correct sorting or not). Once the rule is found, a rule change is performed and the task involves discovering the new sorting rule. The sorting rules are based on perceptual criteria of the elements present on the cards such as color, shape or number. As Miyake (2000) pointed out, the WCST seems to be much more than a test of cognitive flexibility and, according to him, corresponds to a test of high-level executive function, certainly involving cognitive flexibility, but not only this. This task has been considered by different researchers as an inhibition task, a problem-solving task, a categorization task, or other.

Based on the same principle of switching from one process to another on a series of items, several tasks have been proposed that attempt to target an assessment of cognitive flexibility more directly. One of these, often considered a WCST for children, was originally proposed as a flexibility task for preschoolers: the Dimensional Change Card Sort (DCCS) by Frye et al. (1995) – for a recent meta-analysis on this task, see Doebel and Zelazo (2015). In this test, the child must sort two types of test cards (red boats and blue rabbits), matching them to two target cards (a blue boat and a red rabbit). The test consists of two blocks. In the first block, the child must sort the test cards along one dimension (color or shape) and in the second block, the child must sort the same test cards along the other dimension. The instruction is repeated at each trial and the change of dimension is explicitly announced.

We can also mention the Brixton Spatial Anticipation Test, by Burgess and Shallice (1996), which is a test quite similar to the WCST. This test consists of a prediction of displacement according to a rule to be discovered. The rule changes during the test and thus requires the discovery of the new rule. This version is often considered less time consuming than the WCST and more accessible to patients. This test has been adapted for preschoolers by Lehto and Uusitalo (2006) (Brixton Preschool). The child has to predict the spatial location of a character that changes at each trial according to a rule to be discovered on the basis of feedback. In this version, a change of rule also occurs during the test.

The common feature of the above tests is that they require flexible switching from one rule to another on a set of items. Other tasks, on the other hand, require a change in stimulus processing, not between several blocks of items, but from one item to another. One example is the “plus minus” task (Jersild 1927), which compares the performance obtained when performing simple operations (addition or subtraction) without the need to switch to those obtained when performing a series of operations involving a systematic switch between these two simple operations.

This procedure can be seen as the basis of the task switching paradigm, which is used in a great deal of research on processing flexibility in adults (Mayr 2001; Monsell 2003; Schuch and Koch 2003; Mayr and Bell 2006).

Other tasks built on this task switching format can be cited as classic cognitive flexibility tasks and are still widely used, such as the number-letter task (Rogers and Monsell 1995). In this task, pairs of numbers and letters (e.g. 4F) are presented either at the top or bottom of a screen. Depending on the location of the number-letter pair on the screen (top or bottom), a question has to be answered about the number (even or odd?), or about the letter (consonant or vowel?).

The local-global task (Miyake et al. 2000) presents a geometric figure (often referred to as a “Navon figure”; Navon (1977)), in which the shape of a global figure (e.g. a triangle) is composed of other figures, local figures this time, which are much smaller (e.g. squares). A cue (e.g. the color of the figure) tells participants whether to give the number of lines used to compose the figure (e.g. 1 for a circle, 2 for an X, 3 for a triangle, or 4 for a square) for either the global figure or the local figure.

Like the two tasks just presented, some tasks are qualified as cueing, as a cue (usually visual or auditory) signals to the participant what processing they should perform on the stimuli presented to them. For example, in the Color Shape Task (Miyake and Friedman 2012), a cue is given to the participant (C or S) to indicate whether they will have to judge the color (C for color, red or green) or the shape (S for shape, circle or triangle) of the stimulus that will appear. The switching cost is calculated by comparing the reaction times between repeated items (when the processing of the presented item is the same as for the previous item, color then color, for example) and switching items (when the processing of the presented item is different from the previous item, color then shape, for example).

In the TMT (Reitan and Wolfson 1993), the participant must switch from processing a sequence of letters in alphabetical order (A, B, C, etc.) to processing a sequence of numbers in ascending order (1, 2, 3, etc.), alternating between the two processes from one item to the next. Several numbers and letters are placed on a sheet of paper and the participant has to connect the elements with a pencil, going from the first letter (A), to the first number (1), to the second letter (B), and so on (A, 1, B, 2, C, 3, etc.).

A simplified version of this test exists to make it accessible to preschoolers, the TMT for preschoolers (Espy and Cwik 2004). In this test, a sheet of paper shows dogs and bones of different sizes. The child is asked to stamp dogs in order of size (smallest to largest), while stamping the bones corresponding to the size of the dog as they go. The child must stamp the smallest dog, then the smallest bone, then the second dog, the second bone, etc. However, this version for children does not seem quite satisfactory, at least if it is to be used in conjunction with the adult version, because it does not allow for the same type of change to be assessed. The adult version requires switching from one task to another (connecting numbers and connecting letters), whereas the child version only proposes switching between two identical tasks: connecting according to size, certainly by alternating dog and bone, but the task remains identical.

Another adult version with a version for children exists: the Color Trail Test (CTT) (D’Elia et al. 1996) and the Children’s Color Trail Test (CCTT) (Williams et al. 1995), this time being more similar to the adult version. In both cases, the test consists of alternating between two series of numbers, one in pink circles, the other in yellow circles. These versions are simpler than the original version, proposing to alternate between two identical tasks (connecting the sequence of numbers, although alternating according to the color of the items). However, they are still useful in some cases and have the advantage of proposing two equivalent versions, allowing for a comparison of the results of children and adults.