Discussion

The present experiment probed the strategic influence of implicit goal information imparted by test question format on evaluative performance across different

domains. This followed from the findings of the recognition experiments conducted in Chapter 2, in which question format was found to impart goal emphasis to particular decision categories and instil strategies that directly influenced memory decision outcomes. The present experiment interrogated whether the question emphasis effect was rooted in cross-domain cognitive control mechanisms via presentation of four item discrimination tasks performed by the same sample of subjects: the

semantic judgement task, the colour perception task, the episodic temporal judgement task and the episodic recognition task. The results revealed variable influences of question emphasis manipulations across behavioural measures, with a general lack of evidence in support of cross-domain emphasis effects emerging in analyses of “primary” measures of yes/no decision-making, including SDT estimates of criterion bias, as well as the accuracy and time taken to endorse task decision categories. However, consistent cross-domain emphasis effects were observed in the final set of “secondary” proportion confidence analyses, which segregated the proportion of endorsements of decision categories in each task according to self- rated confidence, and demonstrated reliable effects of question emphasis in shifting the proportion of low confidence decisions across the four tasks. The findings serve to highlight the intricacies in elucidating control processes that exert “general” influences on cognitive processing across different domains.

The establishment of the question emphasis effect in the previous chapter centred on analyses of SDT criterion and decision accuracy measures of recognition

144 the likelihood of endorsing emphasised decisions, whilst improving the accuracy of emphasised endorsements when made. These effects of question emphasis on recognition behaviour were demonstrated to be reliable via replication of these concomitant effects on criterion and decision accuracy in two separate experiments presented in Chapter 2, as well as in an independent online study recruiting a large sample (Mill & O’Connor, 2014). However, in the present experiment, the only reliable effect of question emphasis on these two behavioural measures was

exclusive to the semantic task. As with the findings of the previous chapter, question emphasis shifted SDT criterion to reduce the frequency of endorsing emphasised semantic decisions, whilst concurrently increasing the accuracy of these emphasised endorsements. Hence, the SDT criterion and decision accuracy effects in the

semantic task suggest that question format might serve as a hitherto unaccounted for source of strategic bias on “primary” yes/no response measures in laboratory tests of semantic memory. Response biases operating on semantic memory have been alluded to previously, albeit as nested within recognition tasks that engage aspects of semantic processing, such as the proposed criterion-gating of semantic elaboration of retrieved content in the remember/know procedure (Donaldson, 1996) and in the recognition of emotional stimuli (Kapucu, Rotello, Ready & Seidl, 2008; Talmi & Moscovitch, 2004). The findings of the present experiment suggest that tasks directly assessing semantic memory might also be subject to goal-driven strategic biases.

However, rather than describing sources of bias specific to semantic evaluation, the primary aim of the present experiment was to elucidate strategic biases that manifest across different cognitive domains. Indeed, the question emphasis effects on SDT criterion and decision accuracy in the semantic task did not generalize to the other

145 discrimination tasks. Of particular note is the failure to recover question effects on criterion and decision accuracy in the current recognition task, which was of a broadly similar format to the recognition tasks of the previous chapter that yielded reliable question effects on these measures. One potential factor accounting for the replication failure is the reduced power afforded by the present recognition task, in that only 60 trials of each question emphasis condition were presented to

participants, whereas 120 trials of each question condition were presented in the Chapter 2 experiment. Hence, it is possible that the present recognition criterion shift, which operated in the expected counter-emphasis direction, would have reached conventional significance if more trials were provided.

Further, the ostensibly minor differences in format between the present recognition task and those of Chapter 2 might nevertheless have introduced significant

behavioural differences, as supported by prior reports of subtle aspects of task format influencing measures of recognition performance (Hicks & Marsh, 1999; Marsh & Hicks, 1998). The implied difficulties in isolating specific strategic influences on recognition performance are substantiated by prior failure to recover reliable biases following more explicit test environment manipulations than the present subtle variations of question format. For instance, both extreme variations in the base rate proportion of old to new items (Herron, Quayle & Rugg, 2003; Cox & Dobbins, 2011) and cueing of likely evidence strength on a trial-by-trial basis (Morell, Gaitan & Wixted, 2002; Stretch & Wixted, 1998b) have been observed to yield surprisingly modest effects on response criterion. An important factor contributing to these mixed findings is participants’ willingness to adopt controlled strategies (Koriat & Goldsmith, 1996) and the related ease of integrating strategies into ongoing evaluative

146 1998b). Hence, the present partial intermixing of the question format manipulations (i.e. question emphasis alternated after 30 trials within each task’s 120 test list) might have contributed to the weak effects on criterion and decision accuracy measures, by increasing the cognitive effort entailed in integrating this source of goal

information into the ongoing analysis of memory strength. This is contrasted with the fully blocked manipulations of question format in the Chapter 2 experiments, which putatively affords easier goal emphasis integration.

A major cause of the difficulty in isolating question emphasis effects in criterion and decision accuracy measures is the observed variance in overall sensitivity across tasks. These cross-task sensitivity differences putatively arise from differences in the underlying evidence strength signals under evaluation in each task domain (Green & Swets, 1966). Variability in evidence strength has been highlighted as a primary impediment in eliciting stable cross-task measures of performance monitoring in the field of metacognition (Lau, 2010; Fleming & Dolan, 2012). Evidence strength

variability is also capable of impacting more directly on “primary” measures of performance, given that evaluative outcomes are widely assumed to emerge from the interaction of evidence strength assessment and higher-order strategic

processes, as postulated in research in episodic (Benjamin, 2007) and non-episodic domains (Cabeza, Ciaramelli, Olson & Moscovitch, 2008; Corbetta & Shulman, 2002). Hence, failure to adequately equate the evidence strength signals might have encouraged differences in the relative contributions of evidence and strategic

processes to evaluative processing in different task domains. For instance, high levels of evidence strength in the colour task (for which overall sensitivity was at ceiling levels) might have served to reduce the general need to engage strategic

147 biases to optimise performance, as is suggested by the broad absence of strategic effects of question format in this task.

Variation in evidence strength across the four tasks might also have enhanced strategic influences other than the question emphasis bias, such as the observed strategic caution towards particular decision categories within tasks (as

demonstrated by the patterns of negative absolute criterion placement in the

semantic and colour tasks, and complementary effects of decision type on decision accuracy and RT). Other extraneous strategic influences might have arisen from the online monitoring of the different performance levels across the different tasks. For instance, given the greater difficulty of the episodic recognition and temporal tasks compared to the two non-episodic tasks (as revealed by the overall task

sensitivities), participants might have attempted to counteract the subjective experience of weaker episodic evidence by adopting confirmatory biases acting in converse directions to the question emphasis bias. Similar biases resulting from evidence strength monitoring have been reported in prior recognition research (Hirshman, 1995; see Chapter 1, Section 1.4.). Overall, both the SDT criterion and decision accuracy measures suffered from collapsing across the observed variability in overall levels of evidence strength across tasks. The related variability introduced in the strategic processes engaged during task performance therefore made it harder to isolate the question emphasis bias of primary interest.

Indeed, reliable effects of question emphasis emerged in the proportion confidence analyses that aimed to account for the cross-task variability in evidence strength. Implicit in the proposed dichotomy between evidence strength and strategic processes is the dynamic up-regulation of strategic processes when evidence

148 drives a heightened reliance on strategic sources of diagnostic information to reach adaptive decision outcomes, as documented in diverse forms of decision-making (Kahneman, Slovic & Tversky, 1982) and perception (Whiteley & Sahani, 2008). Hence, stronger question emphasis effects were expected in the present experiment for the proportion confidence analyses, which segregated decision proportions according to levels of confidence and inferred levels of evidence uncertainty. Decisions rendered with low confidence were assumed to reflect high levels of uncertainty, as predicated on similar assumptions in functional neuroimaging studies of decision-making in episodic (Henson et al., 2000; Fleck et al., 2006) and visual domains (Fleming et al., 2012). The results demonstrated reliable cross-domain reductions in the endorsements of decisions emphasised by the question,

specifically at low levels of confidence and heightened uncertainty. Indeed, the only proportion low confidence shift that failed to reach significance was observed in the colour task, in which evidence strength was at ceiling levels and the scope for the question emphasis bias to impact on behaviour was reduced.

Further, the present strategic confidence shifts acted in the same “counter-

emphasis” direction as the question biases described in the previous chapter i.e. in reducing the likelihood of endorsing emphasised decisions. The fact that these strategic shifts were confined to low confidence decisions (and, in the case of the temporal task, manifested despite presence of a converse “pro-emphasis” criterion bias) corroborates allusion in the previous chapter to the mediating influence of evidence strength uncertainty on environmental strategies. To clarify, stronger question emphasis effects were obtained in Experiment 2 (Sections 2.2. and 2.3.) when episodic evidence was systematically weakened by encoding tasks that yielded shallow levels-of-processing (LOP; Craik & Lockhart, 1972), with

149 progressively weaker question emphasis effects elicited following intermediate and deep LOP encoding tasks.

The selective impact of strategic question effects on the low confidence portion of the evidence spectrum also clarifies the relative involvement of the ‘retrieval control’ (or ‘evidence control’, to use a less domain-specific term) and ‘decision control’ sub- processes defined in Chapter 1 (see Section 1.3.). If question emphasis shifts were underpinned by evidence control mechanisms, selective impacts on the proportion of high confidence decisions would be expected, resulting from heightened attempts to recover stronger evidence for emphasised decisions. In this scenario, question emphasis would increase the proportion of emphasised decisions registered at high confidence, consistent with prior suggestion of heightened evidence control leading to heightened recollective source monitoring in episodic evaluation (given that

recollection is typically associated with high confidence responding; Jacoby, Kelley & McElree, 1999; Jacoby, Toth & Yonelinas, 1993). Rather, the observed results bear out the selective impact of question emphasis effects on low confidence decisions, consistent with the recruitment of decision control mechanisms in the face of uncertainty. The findings serve to highlight that environmental manipulations

primarily impact on evaluative performance via the up-regulation of decision control mechanisms, thereby validating the preferential study of this sub-category of

cognitive control during the course of my PhD.

The present question emphasis effects also highlight the potential role for decision confidence as a behavioural index of cross-domain processing. This complements prior report of cross-modality metacognitive processes being elicited in measures of response confidence across different perceptual tasks (Song et al., 2011; see Section 1.6.). The cross-domain consistency of the present confidence effects is

150 especially noteworthy when considering the large differences in overall sensitivity and evidence strength across tasks. The earlier discussion illustrated the propensity for evidence strength variability to impede the isolation of higher-order processes active in different cognitive domains – a problem that is typically controlled by psychophysical methods of performance equation for perceptual domains (e.g. Fleming, Weil, Nagy, Dolan & Rees, 2010) and by levels-of-processing

manipulations for episodic memory domains (as in the previous chapter, Craik & Lockhart, 1972). The present findings illustrate the utility of response confidence as an inferential alternative to these more time-consuming methods of evidence

strength control (especially as overall run time is a key concern in experiments involving a number of task domains). A confidence-based segregation of evidence strength might be especially useful when trying to access a large sample, in which case the psychophysical calibration of each individual’s available evidence strength becomes particularly impracticable. These concerns might become increasingly pertinent with the advent of online methods of psychological experimentation (Birnbaum, 2000).

In conclusion, whilst the findings of the present experiment provide evidence

suggesting that question emphasis effects are indeed underpinned by cross-domain strategic control processes, they nevertheless also serve to emphasise the difficulty in isolating these control processes in overt behaviour. The variable evidence strength signals across different task domains impaired the recovery of cross-task question emphasis in “primary” measures of performance, such as SDT criterion and decision accuracy. Stronger effects in these primary measures might be expected following more explicit manipulations of strategic control. This was demonstrated by a recent study that explicitly manipulated the base rate proportion of presented items

151 in perceptual and episodic discrimination tasks, and observed comparable shifts in diffusion model estimates of response bias across both task domains (White & Poldrack, 2014; see Section 1.6.). Hence, the next experimental chapter

implemented stronger manipulations of goal emphasis (in the form of monetary incentives) with the aim of recovering more pronounced cross-domain strategic effects in primary measures of evaluative performance. These manipulations were applied to the semantic and episodic tasks that have thus far recovered the strongest strategic biases across the four presented experiments. The reduction in presented task domains raised the additional benefits of increasing the trial counts for

conditions of interest in each task (and associated power), as well as reducing the scope for extraneous strategic effects driven by the monitoring of relative

performance across task domains (as discussed previously). This enabled a more targeted interrogation of cognitive control mechanisms capable of influencing behaviour across different evaluative domains.

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Chapter 4: The interaction of explicit goal emphasis and cued