Editorial

What Can we Infer from Double Dissociations?

Research has found substantial negative effects of divided attention (DA) during encoding but less substantial effects when attention is divided during retrieval, an asymmetry which has been interpreted as indicating that different control processes or forms of attention are involved in encoding and retrieval (e.g., Chun & Johnson, 2011; Craik, Govoni, Naveh-Benjamin, & Anderson, 1996; Long, Kuhl, & Chun, 2018). The extant evidence, however, is not strong support for qualitative differences and might simply indicate differential sensitivity. The present experiments document a stronger, double dissociation by focusing on the Attentional Boost Effect (ABE) – a phenomenon in which the detection of targets in a secondary task enhances encoding of co-occurring stimuli. The dual-task interaction account proposes that the classical negative effects produced by dual-task interference are offset by a transient increase in externally-directed attention brought about by target detection. Since externally-directed attention is less valuable for retrieval processes, the ABE should result in a net negative effect when applied in the test phase because the dual-task interference would no longer be offset by the externally-directed boost occurring during target trials. Experiments 1, 2 and 4 confirmed the predictions by showing that test words paired with target stimuli were recognized significantly worse than test words paired with distractor stimuli. In contrast, Experiments 3 and 4 replicated the usual positive effects of the ABE with respect to encoding. We discuss these findings in light of recent theoretical proposals suggesting that encoding and retrieval processes are subserved by different forms of attention (external [perceptual] vs. internal [reflective]). Implications for the Transfer-Appropriate-Processing view of memory are also illustrated.

State-Trace Analysis (STA) is a methodology for investigating the number of latent variables. Recently, a quantitative STA technique based on conjoint monotonic regression and double bootstrap method (STA-CMR) has been proposed. More discussion is needed on the type I error and the statistical power of this technique, as it adopts null hypothesis significance testing (NHST) to draw statistical inference. Because the results of STA are comparable with analysis of variance (ANOVA) in a three-factor experiment with linearity assumption, it is necessary to compare STA-CMR with ANOVA accordingly. This study investigated the type I error and the statistical power of STA-CMR and ANOVA in specific linear and nonlinear models using simulated data. Results demonstrated that both techniques were effective in the linear models, where ANOVA had a greater statistical power and STA-CMR had a more rigorous control of type I error. In the nonlinear models, although STA-CMR worked just as well as in the linear models, ANOVA completely lost its effectiveness. Besides, we found that the estimated type I error rate of STA-CMR was always smaller than the preset significance level in both linear and non-linear models. We suggest that the suppressed type I error rate may be caused by the bootstrap procedure, but the exact causes need further investigation. In conclusion, despite the suppressed type I error rate, STA-CMR can be a useful tool for determining the number of latent variables, particularly in non-linear models.

We review evidence from an extensive single case study in an individual (NB) who underwent a rare left-sided anterior temporal-lobe resection with sparing of the hippocampus. Our study aimed to determine whether memory functions of perirhinal cortex, which was largely removed in the resection, can be impaired against a background of preserved hippocampus-dependent memory processing. This research was guided by the proposal that item-based familiarity assessment relies on contributions of perirhinal cortex, and that the hippocampus plays a unique role in the relational binding of items to episodic contexts, which is critical for recollection. Seven sets of findings have emerged from our research on NB (synthesized from five primary research articles), and from follow-up work in other patients: (i) Familiarity impairments can be selective and be revealed with multiple methods; (ii) selective familiarity and selective recollection impairments can be double dissociated; (iii) selective familiarity impairments show material specificity; (iv) selective familiarity impairments extend to assessment of cumulative lifetime experience; (v) selective familiarity impairments are sensitive to degree of feature overlap between object concepts; (vi) selective familiarity impairments are associated with preserved task-related fMRI signals in the hippocampus; (vii) selective familiarity impairments can be observed in other lesion cases. Despite our main focus on the dual-process framework, we also discuss implications for the functional organization of the medial temporal lobes in broader terms. We argue that our findings shed light on this organization even if the functional specialization of different medial temporal structures is ultimately not fully captured with reference to the cognitive distinction between familiarity and recollection.

Patients with focal frontal lobe damage have long been a crucial source of information about the role of this region in human behavior. This method remains the only means to provide inferentially powerful loss-of-function evidence for many regions within the human frontal lobes. This chapter demonstrates modern focal lesion research methods, focusing on specific subregions within prefrontal cortex, and their contributions to widely studied aspects of executive function and decision-making. Examples of such studies are reviewed in detail, to demonstrate the strengths, limitations, and logic of lesion methods. The evidence provided by such studies is considered in relation to converging evidence from other cognitive neuroscience methods. The tensions between modular and network views of prefrontal function are also addressed. Lesion studies straddle fundamental and clinical neuroscience, allowing basic advances in this area to be readily translated to psychiatric and neurologic disorders. This unique position, as well as the ability to test causal claims, explains the staying power of this classic approach to understanding the brain basis of behavior.