Cue Switching Research Articles

Cue switching in the perception of approximants: Evidence from two English dialects

A surprising dissimilarity is attested in the perception of approximants by speakers of American and Standard Southern British English. Eighteen subjects (6 AE and 12 SSBE) performed an identification task in which they judged whether stimuli were more like /r/ or /w/. The stimuli comprised five sounds, copy-synthesised from a source /r/, where the values of F2 and F3 we adjusted to fall between the frequencies typical for ["turned r"] and [w]. The only significant difference between the two dialect groups' performance occurred with a token in which F3 was at a frequency typical for /r/ and F2 was lowered to that of /w/. AE and SSBE speakers identified this token as /r/ 90% and 59% of the time, respectively. This is unexpected as /r/ in both dialects is characterised by a low F3. However, the difference may be due to the existence of the 'labiodental' variant of /r/ in SSBE. As this variant does not have a low F3, SSBE speakers must tolerate a wider diversity of /r/-types than AE speakers. Therefore, the /r/ category in SSBE may be becoming increasingly defined by F2, rather than F3, which also has implications for the future production of /r/ in this accent

Dissociating cue-related and task-related processes in task inhibition: Evidence from using a 2:1 cue-to-task mapping.

Performance of task sequences is assumed to rely on activation and inhibition of tasks. An empirical marker of task inhibition is the so-called n-2 repetition cost, which is assessed by comparing performance in trial n-2 task repetitions (i.e., ABA) with that in n-2 task switches (i.e., CBA). Current theoretical accounts assume that inhibition acts on the level of task representations (i.e., task sets). However, another potential target of task inhibition could be the representation of the task cue. To decide between these two alternatives, the authors used a 2:1 cue-to-task mapping design. They found significant n-2 task repetition costs both with n-2 cue repetitions and n-2 cue switches. These costs were about equal (Experiment 1), and this data pattern was found for both short and long cuing intervals (Experiment 2). Together, the data suggest that task inhibition acts on task sets and not on cue representations.

Task switching versus cue switching: Using transition cuing to disentangle sequential effects in task-switching performance.

Recent methodological advances have allowed researchers to address confounds in the measurement of task-switch costs in task-switching performance by dissociating cue switching from task switching. For example, in the transition-cuing procedure, which involves presenting cues for task transitions rather than for tasks, cue transitions (cue switches and cue repetitions) and task transitions (task switches and task repetitions) can be examined in a complete factorial design. Transition cuing removes the confound between cue transitions and first-order task transitions, but it introduces a confound between cue transitions and longer task sequences. In the present study, transition cuing was studied with two cues per transition (REPEAT and AGAIN for task repetitions; SWITCH and CHANGE for task switches), enabling a partial deconfounding of cue transitions and task sequences. Two experiments revealed robust sequential effects, with higher order task transitions affecting performance when cue transitions were held constant and with cue transitions affecting performance when task sequences were held constant. Methodological and theoretical implications of these findings for research on task switching are discussed.

Task switching is not cue switching

With the aim of reducing cognitive control in task switching to simpler processes, researchers have proposed in a series of recent studies that there is little more to switching tasks than switching cues. The present study addresses three questions concerning this reduction hypothesis. First, does switching cues account for all relevant variance associated with switching tasks? Second, how well does this hypothesis generalize beyond the experimental procedure from which it was developed? Third, how well does this new procedure preserve relevant measures such as task-switch cost? The answers (no; not very; not very) suggest that task switching does not reduce to cue switching.

What matters in the cued task-switching paradigm: Tasks or cues?

Schneider and Logan (2006) recently showed that cue-switch and task-switch costs are sensitive to the relative probability of cue switches versus task switches. From this they concluded that task-switch costs reflect priming of cue-cue transitions rather than actual task-switching operations. However, because this design confounded probability of specific cue transitions with probability of task switches, the results could also reflect task-switch-level adjustments. The present experiment (N = 80) pits the critical prediction of the cue-priming account, namely that costs for high-probability cue-cue transitions are smaller than for low-probability cue-cue transitions, against the main prediction of the switch-probability account, namely that switch probability, irrespective of specific cue-cue transitions, determines switch costs. Whereas the cue-priming prediction was rejected, a specific version of the probability account--that subjects are sensitive to the probability of a task switch, given a cue switch--was fully confirmed. Thus, tasks are in fact the critical representational units that determine task-switch cost.

Methodological and empirical issues when dissociating cue-related from task-related processes in the explicit task-cuing procedure

In the explicit cuing version of the task-switching paradigm, each individual task is indicated by a unique task cue. Consequently, a task switch is accompanied by a cue switch. Recently, it has been proposed that priming of cue encoding contributes to the empirically observed switch costs. This proposal was experimentally supported by using a 2:1 mapping of cues to tasks, so that a cue switch does not necessarily imply a task switch. The results indeed suggested a substantial contribution of "cue-switch costs" to task-switch costs. Here we argue that the 2:1 mapping potentially leads to an underestimation of "pure" task-switch costs. To support this argument, we report the results of a new study in which we used "transition cues" that indicate the identity of the current task based on the identity of the preceding task. This new type of cue allows a full factorial manipulation of cue switches and task switches because it includes the condition in which a cue repetition can also indicate a task switch (i.e., when the "switch" cue is repeated). We discuss the methodological implications and argue that the present approach has merits relative to the previously used 2:1 mapping of cues to tasks.

Is perseveration caused by inhibition failure? Evidence from preschool children’s inferences about word meanings

Four studies examined the relation between children’s cognitive inhibition and flexibility in a lexical inference task. Children’s linguistic flexibility was assessed by the Flexible Induction of Meaning (FIM) test ( Deák, 2000a), which requires that children shift inferences about the meanings of several words for novel objects. In Study 1, 54 3-year-olds either were trained between blocks of problems, for a delay of 3 min, or received no training or delay. Training delays did not influence perseveration. In Study 2 ( N=72 3- and 4-year-olds’) novel word problems were grouped either to increase the frequency of cue switches (i.e., reduce response “set”) or minimize the interval between problems about the same objects. Again, no effect was found. In Study 3, 48 3- and 4-year-olds completed 6 preliminary trials; in a high interference group these trials generated a response set to be inhibited upon the first switch to a new cue context. This group did not perseverate more than a control group. There was no association between FIM perseveration and a Stroop-like test of verbal inhibition though both were marginally related to receptive vocabulary. In study 4 (48 3- and 4-year-olds), FIM was again unrelated to Stroop performance, but was related to the ability to tell whether a situation or problem is indeterminate. Thus, flexibility across semantic inferences is not influenced by timing, order, and number of pre-switch problems and is not predicted by individual differences in a test of verbal inhibition. However previously reported age and individual differences in flexible induction of word meanings are robust and related to vocabulary and logical ability.

Relative Perceptual Cue Strength for Voiced Stop Consonants

The relative strength of noise bursts and vocalic transitions as perception cues of word initial voiced stop consonants in CVC nonsense utterances was investigated using a tape splicing technique. All possible combinations of noise bursts and vocalic transitions in CVC utterances (using /b, d, g/ as initial consonants, /i, æ, a, u/ as vowel, and /z/ as the final consonant) were obtained by tape splicing-substitution techniques. Temporal segmentation was accomplished by inserting a piece of splicing tape before each utterance. A sonogram was made on which the location of the tape splice in relation to the utterance was shown. Measurement of the sonogram and conversion to distance along the tape allowed for a precise tape splice for substitutions of noise bursts and vocalic transitions (cue switching). The first 10 msec of noise burst and the following 50 msec vocalic transition were systematically substituted for presentation to a group of listeners. For example, each listener heard /biz/ produced in a normal manner, a silence inserted for the /b/ burst plus /iz/, and /b/ burst attached to all combinations of /iz/ which originally had been produced with either /d/ or /g/ as the initial consonant. Similiarly vocalic transitions were varied, so that each transition was substituted into all other CVC utterances. The results of this investigation indicate a slight preference for listeners to identify CVC syllables on the basis of the noise burst rather than on the basis of the transitional information.

The scheduling of discriminative cues in successive discrimination learning

The proportion of negative cues and the frequency of switching the discriminative cues in the presentation sequence of the successive discrimination paradigm were treated in a 2 by 2 design, having nine rats per cell. In support of a suggestion by Hull, negative-to-positive cue ratios larger than one increased discrimination accuracy following pretraining with the positive cue. To a lesser extent, the data also suggested that infrequent cue switches led to better discrimination than frequent ones, a finding noted to be consistent with the cue ratio outcome but in disagreement with the Bush-Mosteller frequent cue switching principle.